diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index 17f7e6112a..bcdb12fafd 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -3177,16 +3177,15 @@ nvim_buf_get_extmarks({buf}, {ns_id}, {start}, {end}, {opts})
     If `end` is less than `start`, marks are returned in reverse order.
     (Useful with `limit`, to get the first marks prior to a given position.)
 
-    Note: For a reverse range, `limit` does not actually affect the traversed
-    range, just how many marks are returned
-
-    Note: when using extmark ranges (marks with a end_row/end_col position)
-    the `overlap` option might be useful. Otherwise only the start position of
-    an extmark will be considered.
-
-    Note: legacy signs placed through the |:sign| commands are implemented as
-    extmarks and will show up here. Their details array will contain a
-    `sign_name` field.
+    Note:
+    • For a reverse range, `limit` does not actually affect the traversed
+      range, just how many marks are returned
+    • When using extmark ranges (marks with a end_row/end_col position) the
+      `overlap` option might be useful. Otherwise only the start position of
+      an extmark will be considered.
+    • The |:marks| command can list extmarks.
+    • Legacy signs placed through the |:sign| commands are implemented as
+      extmarks. Their details array will contain a `sign_name` field.
 
     Example: >lua
         local api = vim.api
diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index b3a3088d6f..a72a8212a6 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -1575,6 +1575,8 @@ vim.show_pos({buf}, {row}, {col}, {filter})                   *vim.show_pos()*
 
     Can also be shown with `:Inspect`.                              *:Inspect*
 
+    See also |:marks| to list all extmarks.
+
     Example: To bind this function to the vim-scriptease inspired `zS` in
     Normal mode: >lua
         vim.keymap.set('n', 'zS', vim.show_pos)
diff --git a/runtime/doc/motion.txt b/runtime/doc/motion.txt
index 147399bcbc..1b4daa36e2 100644
--- a/runtime/doc/motion.txt
+++ b/runtime/doc/motion.txt
@@ -877,7 +877,9 @@ g'{mark}  g`{mark}
 			See also |:keepjumps|.
 
 						*:marks*
-:marks			List all the current marks (not a motion command).
+:marks			List all marks, and |extmarks| namespaces (use ":marks
+			{ns}" to list them).
+
 			The |'(|, |')|, |'{| and |'}| marks are not listed.
 			The first column has number zero.
 						*E283*
@@ -885,7 +887,10 @@ g'{mark}  g`{mark}
 			motion command).  For example: >
 				:marks aB
 <			to list marks 'a' and 'B'.
-
+			If {arg} is |extmark| |namespace|, the extmarks for
+			current buffer are listed: >
+				:marks nvim.multicursor
+<
 							*:delm* *:delmarks*
 :delm[arks] {marks}	Delete the specified marks.  Marks that can be deleted
 			include A-Z and 0-9.  You cannot delete the ' mark.
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index 4ee40a9218..eed1f8deca 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -213,6 +213,8 @@ EDITOR
   • The |cmdwin-char| is shown via 'statuscolumn'.
 • |gf| and |<cfile>| support `file://…` URIs.
 • |:log| opens log files.
+• |:marks| can list |extmarks| for a given |namespace|.
+• |:marks| gained tab-completion.
 • |:restart| saves/restores the current session (window layout, buffers, …).
   • |:restart!| (with a bang "!") does not save/restore the session.
 • |ZR| restarts Nvim (|:restart|).
diff --git a/runtime/doc/vimfn.txt b/runtime/doc/vimfn.txt
index 538cac7dac..c0915ee20d 100644
--- a/runtime/doc/vimfn.txt
+++ b/runtime/doc/vimfn.txt
@@ -3954,7 +3954,8 @@ getmarklist([{buf}])                                             *getmarklist()*
 		If the optional {buf} argument is specified, returns the
 		local marks defined in buffer {buf}.  For the use of {buf},
 		see |bufname()|.  If {buf} is invalid, an empty list is
-		returned.
+		returned.  For a |prompt-buffer| the result includes the
+		|':| mark.
 
 		Each item in the returned List is a |Dict| with the following:
 		    mark   name of the mark prefixed by "'"
diff --git a/runtime/lua/vim/_core/marks.lua b/runtime/lua/vim/_core/marks.lua
new file mode 100644
index 0000000000..63acbad83f
--- /dev/null
+++ b/runtime/lua/vim/_core/marks.lua
@@ -0,0 +1,172 @@
+--- Marks functionality
+--- - |:marks| command/completion
+
+local api = vim.api
+local util = require('vim._core.util')
+local N_ = vim.fn.gettext
+
+local M = {}
+
+--- Names of the namespaces that have extmarks in the current buffer, sorted.
+--- @return string[]
+local function buf_namespaces()
+  local names = {} ---@type string[]
+  for name, id in pairs(api.nvim_get_namespaces()) do
+    if #api.nvim_buf_get_extmarks(0, id, 0, -1, { limit = 1 }) > 0 then
+      names[#names + 1] = name
+    end
+  end
+  table.sort(names)
+  return names
+end
+
+--- Completion for ":marks {arg}":
+--- - set marks (buffer-local and global)
+--- - extmark namespaces (buffer-local)
+--- @return string[]
+function M.complete()
+  local names = {} ---@type string[]
+  for _, list in ipairs({ vim.fn.getmarklist(api.nvim_get_current_buf()), vim.fn.getmarklist() }) do
+    for _, m in ipairs(list) do
+      names[#names + 1] = m.mark:sub(2) -- "'a" => "a"
+    end
+  end
+  table.sort(names)
+  return vim.list_extend(names, buf_namespaces())
+end
+
+--- ":marks {ns}": lists the extmarks of namespace {ns} in the current buffer.
+--- @param ns string
+--- @return boolean handled false: {ns} is not a namespace (it is a set of mark names)
+function M.show(ns)
+  local id = api.nvim_get_namespaces()[ns]
+  if not id then
+    return false
+  end
+  local extmarks = api.nvim_buf_get_extmarks(0, id, 0, -1, {})
+  if #extmarks == 0 then
+    api.nvim_echo({ { ('No extmarks in this buffer for namespace "%s"'):format(ns) } }, false, {})
+    return true
+  end
+  local chunks = { { ('%6s %5s  %4s %s'):format('id', 'line', 'col', 'text'), 'Title' } }
+  for _, m in ipairs(extmarks) do
+    local text = api.nvim_buf_get_lines(0, m[2], m[2] + 1, false)[1] or ''
+    chunks[#chunks + 1] = { ('\n%6d %5d  %4d %s'):format(m[1], m[2] + 1, m[3], vim.trim(text)) }
+  end
+  api.nvim_echo(chunks, false, { kind = 'list_cmd' })
+  return true
+end
+
+--- The line at mark line {lnum}, sans leading whitespace, truncated to fit in the window
+--- (cells), like C mark_line().
+--- @param lnum integer
+--- @return string
+local function mark_line(lnum)
+  if lnum > api.nvim_buf_line_count(0) then
+    return '-invalid-'
+  end
+  local text = api.nvim_buf_get_lines(0, lnum - 1, lnum, false)[1]:gsub('^%s+', '')
+  local limit = vim.o.columns - 15
+  if vim.fn.strdisplaywidth(text) < limit then
+    return text
+  end
+  local keep = {} ---@type string[]
+  local width = 0
+  for _, c in ipairs(vim.fn.split(text, [[\zs]])) do
+    width = width + vim.fn.strdisplaywidth(c)
+    if width >= limit then
+      break
+    end
+    keep[#keep + 1] = c
+  end
+  return table.concat(keep)
+end
+
+--- ":marks [arg]" (|ex_cmds.lua| "marks" => C ex_marks() => this).
+--- @param args vim._core.ExCmdArgs
+function M.ex_marks(args)
+  local arg = args.args ~= '' and args.args or nil
+
+  -- ":marks {ns}": list namespace's extmarks, or fallthrough if unknown.
+  if arg and #arg > 1 and M.show(arg) then
+    return
+  end
+
+  local curbuf = api.nvim_get_current_buf()
+  local marks = {} ---@type table<string,{mark:string, pos:integer[], file?:string}>
+  for _, list in ipairs({ vim.fn.getmarklist(curbuf), vim.fn.getmarklist() }) do
+    for _, m in ipairs(list) do
+      marks[m.mark:sub(2)] = m
+    end
+  end
+
+  -- "<" and ">" are shown as where they will jump to: start before end.
+  local vs, ve = marks['<'], marks['>']
+  if vs and ve then
+    local s, e = vs.pos, ve.pos
+    if s[2] > e[2] or (s[2] == e[2] and s[3] > e[3]) then
+      vs.pos, ve.pos = e, s
+    end
+  elseif ve and not vs then
+    marks['<'], marks['>'] = ve, nil
+  end
+
+  --- The "file/text" column: the text at the mark if it is in the current buffer (highlighted
+  --- as "Directory", like C show_one_mark()), else the file name.
+  --- @param m {pos:integer[], file?:string}
+  --- @return string text, string? hl
+  local function displayname(m)
+    if m.pos[1] == curbuf then
+      return mark_line(m.pos[2]), 'Directory'
+    elseif m.pos[1] == 0 then
+      return m.file or '', nil
+    end
+    return vim.fn.fnamemodify(vim.fn.bufname(m.pos[1]), ':~'), nil
+  end
+
+  -- Fixed :marks order.
+  local order = { "'" }
+  for _, range in ipairs({ { 'a', 'z' }, { 'A', 'Z' }, { '0', '9' } }) do
+    for b = range[1]:byte(), range[2]:byte() do
+      order[#order + 1] = string.char(b)
+    end
+  end
+  vim.list_extend(order, { '"', '[', ']', '^', '.', ':', '<', '>' })
+
+  local filtered = require('vim._core.ex_cmd').filter
+  local chunks = {} ---@type [string, string?][]
+  for _, name in ipairs(order) do
+    local m = marks[name]
+    if m and (not arg or arg:find(name, 1, true)) then
+      local text, hl = displayname(m)
+      if not filtered(args.smods.filter, text) then
+        chunks[#chunks + 1] = { ('\n %s %6d %4d '):format(name, m.pos[2], m.pos[3] - 1) }
+        if text ~= '' then
+          chunks[#chunks + 1] = { text, hl }
+        end
+      end
+    end
+  end
+
+  if #chunks == 0 then
+    if arg then
+      util.echo_err(N_('E283: No marks matching "%s"'):format(arg))
+      return
+    end
+    api.nvim_echo({ { N_('No marks set') } }, false, {})
+  else
+    table.insert(chunks, 1, { N_('\nmark line  col file/text'), 'Title' })
+    api.nvim_echo(chunks, false, { kind = 'list_cmd' })
+  end
+
+  if not arg then
+    -- By default, list extmarks namespaces (but not their extmarks).
+    local names = buf_namespaces()
+    if #names > 0 then
+      local msg = ('Extmark namespaces (use ":marks {ns}"): %s'):format(table.concat(names, ', '))
+      api.nvim_echo({ { msg } }, false, {})
+    end
+  end
+end
+
+return M
diff --git a/runtime/lua/vim/_inspector.lua b/runtime/lua/vim/_inspector.lua
index 5a39006e9c..2ae357a700 100644
--- a/runtime/lua/vim/_inspector.lua
+++ b/runtime/lua/vim/_inspector.lua
@@ -151,6 +151,8 @@ end
 ---
 ---Can also be shown with `:Inspect`. [:Inspect]()
 ---
+---See also |:marks| to list all extmarks.
+---
 ---Example: To bind this function to the vim-scriptease
 ---inspired `zS` in Normal mode:
 ---
diff --git a/runtime/lua/vim/_meta/api.gen.lua b/runtime/lua/vim/_meta/api.gen.lua
index d5208ce596..88ffde519a 100644
--- a/runtime/lua/vim/_meta/api.gen.lua
+++ b/runtime/lua/vim/_meta/api.gen.lua
@@ -409,8 +409,8 @@ function vim.api.nvim_buf_get_commands(buf, opts) end
 --- text span range is deleted. See also the key `invalidate` in |nvim_buf_set_extmark()|.
 function vim.api.nvim_buf_get_extmark_by_id(buf, ns_id, id, opts) end
 
---- Gets `extmarks` in "traversal order" from a `charwise` region defined by
---- buffer positions (inclusive, 0-indexed `api-indexing`).
+--- Gets `extmarks` in "traversal order" from a `charwise` region defined by buffer positions
+--- (inclusive, 0-indexed `api-indexing`).
 ---
 --- Region can be given as (row,col) tuples, or valid extmark ids (whose
 --- positions define the bounds). 0 and -1 are understood as (0,0) and (-1,-1)
@@ -424,16 +424,14 @@ function vim.api.nvim_buf_get_extmark_by_id(buf, ns_id, id, opts) end
 --- If `end` is less than `start`, marks are returned in reverse order.
 --- (Useful with `limit`, to get the first marks prior to a given position.)
 ---
---- Note: For a reverse range, `limit` does not actually affect the traversed
---- range, just how many marks are returned
----
---- Note: when using extmark ranges (marks with a end_row/end_col position)
---- the `overlap` option might be useful. Otherwise only the start position
---- of an extmark will be considered.
----
---- Note: legacy signs placed through the `:sign` commands are implemented
---- as extmarks and will show up here. Their details array will contain a
---- `sign_name` field.
+--- Note:
+--- - For a reverse range, `limit` does not actually affect the traversed range, just how many marks
+---   are returned
+--- - When using extmark ranges (marks with a end_row/end_col position) the `overlap` option might
+---   be useful. Otherwise only the start position of an extmark will be considered.
+--- - The `:marks` command can list extmarks.
+--- - Legacy signs placed through the `:sign` commands are implemented as extmarks. Their details
+---   array will contain a `sign_name` field.
 ---
 --- Example:
 ---
diff --git a/runtime/lua/vim/_meta/vimfn.gen.lua b/runtime/lua/vim/_meta/vimfn.gen.lua
index 5fa3910c0a..252425d2fe 100644
--- a/runtime/lua/vim/_meta/vimfn.gen.lua
+++ b/runtime/lua/vim/_meta/vimfn.gen.lua
@@ -3539,7 +3539,8 @@ function vim.fn.getloclist(nr, what) end
 --- If the optional {buf} argument is specified, returns the
 --- local marks defined in buffer {buf}.  For the use of {buf},
 --- see |bufname()|.  If {buf} is invalid, an empty list is
---- returned.
+--- returned.  For a |prompt-buffer| the result includes the
+--- |':| mark.
 ---
 --- Each item in the returned List is a |Dict| with the following:
 ---     mark   name of the mark prefixed by "'"
diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 246eb9fd88..be16ea3470 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -232,8 +232,8 @@ nvim_buf_get_extmark_by_id(Buffer buf, Integer ns_id, Integer id, Dict(get_extma
   return extmark_to_array(extmark, false, details, hl_name, arena);
 }
 
-/// Gets |extmarks| in "traversal order" from a |charwise| region defined by
-/// buffer positions (inclusive, 0-indexed |api-indexing|).
+/// Gets |extmarks| in "traversal order" from a |charwise| region defined by buffer positions
+/// (inclusive, 0-indexed |api-indexing|).
 ///
 /// Region can be given as (row,col) tuples, or valid extmark ids (whose
 /// positions define the bounds). 0 and -1 are understood as (0,0) and (-1,-1)
@@ -247,16 +247,14 @@ nvim_buf_get_extmark_by_id(Buffer buf, Integer ns_id, Integer id, Dict(get_extma
 /// If `end` is less than `start`, marks are returned in reverse order.
 /// (Useful with `limit`, to get the first marks prior to a given position.)
 ///
-/// Note: For a reverse range, `limit` does not actually affect the traversed
-/// range, just how many marks are returned
-///
-/// Note: when using extmark ranges (marks with a end_row/end_col position)
-/// the `overlap` option might be useful. Otherwise only the start position
-/// of an extmark will be considered.
-///
-/// Note: legacy signs placed through the |:sign| commands are implemented
-/// as extmarks and will show up here. Their details array will contain a
-/// `sign_name` field.
+/// Note:
+/// - For a reverse range, `limit` does not actually affect the traversed range, just how many marks
+///   are returned
+/// - When using extmark ranges (marks with a end_row/end_col position) the `overlap` option might
+///   be useful. Otherwise only the start position of an extmark will be considered.
+/// - The |:marks| command can list extmarks.
+/// - Legacy signs placed through the |:sign| commands are implemented as extmarks. Their details
+///   array will contain a `sign_name` field.
 ///
 /// Example:
 ///
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index 01e2eb6d9e..b37c40155d 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -1337,6 +1337,7 @@ char *addstar(char *fname, size_t len, int context)
         || context == EXPAND_LOG
         || context == EXPAND_PACKDEL
         || context == EXPAND_PACKUPDATE
+        || context == EXPAND_MARKS
         || context == EXPAND_LUA) {
       retval = xstrnsave(fname, len);
     } else {
@@ -2352,6 +2353,10 @@ static const char *set_context_by_cmdname(const char *cmd, cmdidx_T cmdidx, expa
     xp->xp_context = EXPAND_CHECKHEALTH;
     break;
 
+  case CMD_marks:
+    xp->xp_context = EXPAND_MARKS;
+    break;
+
   case CMD_log:
     xp->xp_context = EXPAND_LOG;
     break;
@@ -2940,9 +2945,15 @@ static char *get_arg1_from_lua(char *lua, expand_T *xp, int idx)
   return NULL;
 }
 
-/// Completion for |:log| command.
-///
-/// Given to ExpandGeneric() to obtain `:log` completion.
+/// Completion for the |:marks| command. Given to ExpandGeneric().
+/// @param[in] xp  Expandy thing 🤷
+/// @param[in] idx  Index of the item.
+static char *get_marks_arg(expand_T *xp, int idx)
+{
+  return get_arg1_from_lua("return require'vim._core.marks'.complete(...)", xp, idx);
+}
+
+/// Completion for |:log| command. Given to ExpandGeneric().
 /// @param[in] xp  Expandy thing 🤷
 /// @param[in] idx  Index of the item.
 static char *get_log_arg(expand_T *xp, int idx)
@@ -2950,9 +2961,7 @@ static char *get_log_arg(expand_T *xp, int idx)
   return get_arg1_from_lua("return require'vim._core.ex_cmd'.log_complete(...)", xp, idx);
 }
 
-/// Completion for |:lsp| command.
-///
-/// Given to ExpandGeneric() to obtain `:lsp` completion.
+/// Completion for |:lsp| command. Given to ExpandGeneric().
 /// @param[in] xp  Expandy thing 🤷
 /// @param[in] idx  Index of the item.
 static char *get_lsp_arg(expand_T *xp, int idx)
@@ -2960,9 +2969,7 @@ static char *get_lsp_arg(expand_T *xp, int idx)
   return get_arg1_from_lua("return require'vim._core.ex_cmd'.lsp_complete(...)", xp, idx);
 }
 
-/// Completion for |:packdel| command.
-///
-/// Given to ExpandGeneric() to obtain `:packdel` completion.
+/// Completion for |:packdel| command. Given to ExpandGeneric().
 /// @param[in] xp  Expandy thing.
 /// @param[in] idx  Index of the item.
 static char *get_packdel_arg(expand_T *xp, int idx)
@@ -2970,9 +2977,7 @@ static char *get_packdel_arg(expand_T *xp, int idx)
   return get_arg1_from_lua("return require'vim._core.ex_cmd'.packdel_complete(...)", xp, idx);
 }
 
-/// Completion for |:packupdate| command.
-///
-/// Given to ExpandGeneric() to obtain `:packupdate` completion.
+/// Completion for |:packupdate| command. Given to ExpandGeneric().
 /// @param[in] xp  Expandy thing.
 /// @param[in] idx  Index of the item.
 static char *get_packupdate_arg(expand_T *xp, int idx)
@@ -3022,6 +3027,7 @@ static int ExpandOther(char *pat, expand_T *xp, regmatch_T *rmp, char ***matches
     { EXPAND_SCRIPTNAMES, get_scriptnames_arg, true, false },
     { EXPAND_RETAB, get_retab_arg, true, true },
     { EXPAND_CHECKHEALTH, get_healthcheck_names, true, false },
+    { EXPAND_MARKS, get_marks_arg, true, false },
     { EXPAND_LOG, get_log_arg, true, false },
     { EXPAND_LSP, get_lsp_arg, true, false },
     { EXPAND_PACKDEL, get_packdel_arg, true, false },
diff --git a/src/nvim/cmdexpand_defs.h b/src/nvim/cmdexpand_defs.h
index cc7e9dd595..9fee7fd06f 100644
--- a/src/nvim/cmdexpand_defs.h
+++ b/src/nvim/cmdexpand_defs.h
@@ -133,6 +133,7 @@ enum {
   EXPAND_LOG,
   EXPAND_PACKDEL,
   EXPAND_PACKUPDATE,
+  EXPAND_MARKS,
 };
 
 /// Type used by ExpandGeneric()
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index c423f3b91d..a07e3be0c3 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -4365,7 +4365,8 @@ M.funcs = {
       If the optional {buf} argument is specified, returns the
       local marks defined in buffer {buf}.  For the use of {buf},
       see |bufname()|.  If {buf} is invalid, an empty list is
-      returned.
+      returned.  For a |prompt-buffer| the result includes the
+      |':| mark.
 
       Each item in the returned List is a |Dict| with the following:
           mark   name of the mark prefixed by "'"
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 95139c58e7..99d24be8f5 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -19,6 +19,7 @@
 #include "nvim/eval/typval.h"
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_docmd.h"
 #include "nvim/extmark.h"
 #include "nvim/extmark_defs.h"
 #include "nvim/fold.h"
@@ -26,6 +27,7 @@
 #include "nvim/globals.h"
 #include "nvim/highlight_defs.h"
 #include "nvim/insert.h"
+#include "nvim/lua/executor.h"
 #include "nvim/mark.h"
 #include "nvim/mbyte.h"
 #include "nvim/memline.h"
@@ -909,104 +911,10 @@ static char *mark_line(pos_T *mp, int lead_len)
   return s;
 }
 
-// print the marks
+/// ":marks {arg}": list marks, or namespace-extmarks.
 void ex_marks(exarg_T *eap)
 {
-  char *arg = eap->arg;
-  char *name;
-  pos_T *posp;
-
-  if (arg != NULL && *arg == NUL) {
-    arg = NULL;
-  }
-
-  msg_ext_set_kind("list_cmd");
-  show_one_mark('\'', arg, &curwin->w_pcmark, NULL, true);
-  for (int i = 0; i < NMARKS; i++) {
-    show_one_mark(i + 'a', arg, &curbuf->b_namedm[i].mark, NULL, true);
-  }
-  for (int i = 0; i < NGLOBALMARKS; i++) {
-    if (namedfm[i].fmark.fnum != 0) {
-      name = fm_getname(&namedfm[i].fmark, 15);
-    } else {
-      name = namedfm[i].fname;
-    }
-    if (name != NULL) {
-      show_one_mark(i >= NMARKS ? i - NMARKS + '0' : i + 'A',
-                    arg, &namedfm[i].fmark.mark, name,
-                    namedfm[i].fmark.fnum == curbuf->b_fnum);
-      if (namedfm[i].fmark.fnum != 0) {
-        xfree(name);
-      }
-    }
-  }
-  show_one_mark('"', arg, &curbuf->b_last_cursor.mark, NULL, true);
-  show_one_mark('[', arg, &curbuf->b_op_start, NULL, true);
-  show_one_mark(']', arg, &curbuf->b_op_end, NULL, true);
-  show_one_mark('^', arg, &curbuf->b_last_insert.mark, NULL, true);
-  show_one_mark('.', arg, &curbuf->b_last_change.mark, NULL, true);
-  if (bt_prompt(curbuf)) {
-    show_one_mark(':', arg, &curbuf->b_prompt_start.mark, NULL, true);
-  }
-
-  // Show the marks as where they will jump to.
-  pos_T *startp = &curbuf->b_visual.vi_start;
-  pos_T *endp = &curbuf->b_visual.vi_end;
-  if ((lt(*startp, *endp) || endp->lnum == 0) && startp->lnum != 0) {
-    posp = startp;
-  } else {
-    posp = endp;
-  }
-  show_one_mark('<', arg, posp, NULL, true);
-  show_one_mark('>', arg, posp == startp ? endp : startp, NULL, true);
-
-  show_one_mark(-1, arg, NULL, NULL, false);
-}
-
-/// @param current  in current file
-static void show_one_mark(int c, char *arg, pos_T *p, char *name_arg, int current)
-{
-  static bool did_title = false;
-  bool mustfree = false;
-  char *name = name_arg;
-
-  if (c == -1) {  // finish up
-    if (did_title) {
-      did_title = false;
-    } else {
-      if (arg == NULL) {
-        msg(_("No marks set"), 0);
-      } else {
-        semsg(_("E283: No marks matching \"%s\""), arg);
-      }
-    }
-  } else if (!got_int
-             && (arg == NULL || vim_strchr(arg, c) != NULL)
-             && p->lnum != 0) {
-    // don't output anything if 'q' typed at --more-- prompt
-    if (name == NULL && current) {
-      name = mark_line(p, 15);
-      mustfree = true;
-    }
-    if (!message_filtered(name)) {
-      if (!did_title) {
-        // Highlight title
-        msg_puts_title(_("\nmark line  col file/text"));
-        did_title = true;
-      }
-      msg_putchar('\n');
-      if (!got_int) {
-        snprintf(IObuff, IOSIZE, " %c %6" PRIdLINENR " %4d ", c, p->lnum, p->col);
-        msg_outtrans(IObuff, 0, false);
-        if (name != NULL) {
-          msg_outtrans(name, current ? HLF_D : 0, false);
-        }
-      }
-    }
-    if (mustfree) {
-      xfree(name);
-    }
-  }
+  nlua_call_excmd("vim._core.marks", "ex_marks", eap, &cmdmod, NULL);
 }
 
 // ":delmarks[!] [marks]"
@@ -1963,6 +1871,9 @@ void get_buf_local_marks(const buf_T *buf, list_T *l)
   add_mark(l, S_LEN("']"), &buf->b_op_end, buf->b_fnum, NULL);
   add_mark(l, S_LEN("'^"), &buf->b_last_insert.mark, buf->b_fnum, NULL);
   add_mark(l, S_LEN("'."), &buf->b_last_change.mark, buf->b_fnum, NULL);
+  if (bt_prompt((buf_T *)buf)) {
+    add_mark(l, S_LEN("':"), &buf->b_prompt_start.mark, buf->b_fnum, NULL);
+  }
   add_mark(l, S_LEN("'<"), &buf->b_visual.vi_start, buf->b_fnum, NULL);
   add_mark(l, S_LEN("'>"), &buf->b_visual.vi_end, buf->b_fnum, NULL);
 }
diff --git a/test/functional/core/main_spec.lua b/test/functional/core/main_spec.lua
index 3041b82abb..d185156d7d 100644
--- a/test/functional/core/main_spec.lua
+++ b/test/functional/core/main_spec.lua
@@ -205,6 +205,7 @@ describe('vim._core', function()
       'vim._core.exrc',
       'vim._core.help',
       'vim._core.log',
+      'vim._core.marks',
       'vim._core.options',
       'vim._core.proc',
       'vim._core.server',
diff --git a/test/functional/ex_cmds/marks_spec.lua b/test/functional/ex_cmds/marks_spec.lua
new file mode 100644
index 0000000000..b620c2f038
--- /dev/null
+++ b/test/functional/ex_cmds/marks_spec.lua
@@ -0,0 +1,62 @@
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
+
+local command = n.command
+local eq = t.eq
+local exec_capture = n.exec_capture
+local exec_lua = n.exec_lua
+local feed = n.feed
+local fn = n.fn
+local matches = t.matches
+
+describe(':marks', function()
+  before_each(function()
+    n.clear {}
+    fn.setline(1, { 'one', 'two', 'three' })
+    feed('ma')
+    exec_lua(function()
+      local ns = vim.api.nvim_create_namespace('my.plugin')
+      vim.api.nvim_buf_set_extmark(0, ns, 1, 0, {})
+      vim.api.nvim_buf_set_extmark(0, ns, 2, 1, {})
+      vim.api.nvim_create_namespace('empty.ns') -- no extmarks: not completed, not mentioned
+    end)
+  end)
+
+  it('completes names, lists extmarks', function()
+    -- Completion offers the set marks and the buffer's extmark namespaces.
+    eq({ '"', "'", '.', 'a', 'my.plugin' }, fn.getcompletion('marks ', 'cmdline'))
+    -- :marks (no args) only mentions the namespaces instead of listing their extmarks.
+    local out = exec_capture('marks')
+    matches('mark line  col file/text', out)
+    matches('Extmark namespaces %(use ":marks {ns}"%): my%.plugin', out)
+    eq(nil, out:find('empty%.ns'))
+    -- ":marks {ns}" lists that namespace's extmarks.
+    out = exec_capture('marks my.plugin')
+    matches('id%s+line%s+col text', out)
+    matches('1%s+2%s+0 two', out)
+    matches('2%s+3%s+1 three', out)
+    -- Not a namespace: the usual mark-names filter.
+    matches('mark line  col file/text', exec_capture('marks aB'))
+  end)
+
+  it(':filter on file/text column; E283; "No marks set"', function()
+    fn.setpos("'b", { 0, 2, 1, 0 })
+    local out = exec_capture('filter /two/ marks')
+    matches(' b%s+2%s+0 two', out)
+    eq(nil, out:find(' a ', 1, true)) -- mark a is on "one": filtered out
+    matches('E283: No marks matching "z"', t.pcall_err(command, 'marks z'))
+    -- Bare :marks with every row filtered out.
+    matches('No marks set', exec_capture('filter /xxx-nomatch/ marks'))
+  end)
+
+  it("prompt buffer: ':' mark in getmarklist() and :marks", function()
+    command('enew | set buftype=prompt')
+    feed('ifoo<Esc>')
+    local found = false
+    for _, m in ipairs(fn.getmarklist(fn.bufnr(''))) do
+      found = found or m.mark == "':"
+    end
+    eq(true, found)
+    matches(' :%s+%d+%s+%d+ ', exec_capture('marks'))
+  end)
+end)