diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 4198cfcc97..9e8f661ac7 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -922,9 +922,19 @@ function M.make_floating_popup_options(width, height, opts)
 
   local anchor = ''
 
-  local lines_above = opts.relative == 'mouse' and vim.fn.getmousepos().line - 1
-    or vim.fn.winline() - 1
-  local lines_below = vim.fn.winheight(0) - lines_above
+  local lines_above --- @type integer
+  local lines_below --- @type integer
+  if opts.relative == 'mouse' then
+    lines_above = vim.fn.getmousepos().line - 1
+    lines_below = vim.fn.winheight(0) - lines_above
+  elseif opts.relative == 'editor' then
+    -- No cursor to anchor against; treat the whole editor as space below.
+    lines_above = 0
+    lines_below = vim.o.lines
+  else
+    lines_above = vim.fn.winline() - 1
+    lines_below = vim.fn.winheight(0) - lines_above
+  end
 
   local anchor_bias = opts.anchor_bias or 'auto'
 
@@ -951,7 +961,14 @@ function M.make_floating_popup_options(width, height, opts)
     row = 0
   end
 
-  local wincol = opts.relative == 'mouse' and vim.fn.getmousepos().column or vim.fn.wincol()
+  local wincol --- @type integer
+  if opts.relative == 'mouse' then
+    wincol = vim.fn.getmousepos().column
+  elseif opts.relative == 'editor' then
+    wincol = 0
+  else
+    wincol = vim.fn.wincol()
+  end
 
   if wincol + width + (opts.offset_x or 0) <= vim.o.columns then
     anchor = anchor .. 'W'
diff --git a/test/functional/plugin/lsp/util_spec.lua b/test/functional/plugin/lsp/util_spec.lua
index 8aa78602c5..db7c56495f 100644
--- a/test/functional/plugin/lsp/util_spec.lua
+++ b/test/functional/plugin/lsp/util_spec.lua
@@ -1393,6 +1393,14 @@ describe('vim.lsp.util', function()
           eq('Title', opts.title)
         end)
       end)
+
+      it('anchor is NW for relative = "editor" regardless of cursor #39306', function()
+        feed('G') -- without the fix, cursor on the last line picks an 'S*' anchor
+        local opts = exec_lua(function()
+          return vim.lsp.util.make_floating_popup_options(30, 10, { relative = 'editor' })
+        end)
+        eq('NW', opts.anchor)
+      end)
     end)
 
     describe('open_floating_preview', function()