diff --git a/.gitmodules b/.gitmodules
index 6cbadcbda9..87c1c6b385 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -887,6 +887,9 @@
 [submodule "vendor/grammars/language-typelanguage"]
 	path = vendor/grammars/language-typelanguage
 	url = https://github.com/goodmind/language-typelanguage
+[submodule "vendor/grammars/language-vim9"]
+	path = vendor/grammars/language-vim9
+	url = https://github.com/DanBradbury/language-vim9.git
 [submodule "vendor/grammars/language-viml"]
 	path = vendor/grammars/language-viml
 	url = https://github.com/Alhadis/language-viml
diff --git a/grammars.yml b/grammars.yml
index 13979f0c14..4101c8a713 100644
--- a/grammars.yml
+++ b/grammars.yml
@@ -845,6 +845,8 @@ vendor/grammars/language-turing:
 - source.turing
 vendor/grammars/language-typelanguage:
 - source.tl
+vendor/grammars/language-vim9:
+- source.vim
 vendor/grammars/language-viml:
 - source.vim-snippet
 - source.viml
diff --git a/lib/linguist/heuristics.yml b/lib/linguist/heuristics.yml
index 17d6802916..a09a745036 100644
--- a/lib/linguist/heuristics.yml
+++ b/lib/linguist/heuristics.yml
@@ -1025,6 +1025,11 @@ disambiguations:
     pattern: '\A##fileformat=VCF'
   - language: vCard
     pattern: '\ABEGIN:VCARD'
+- extensions: ['.vim']
+  rules:
+  - language: Vim9 script
+    pattern: '^\s*vim9script(?:\s+noclear)?\s*$'
+  - language: Vim script
 - extensions: ['.w']
   rules:
   - language: OpenEdge ABL
diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 7ea73879c5..00e0b7a160 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -8277,6 +8277,18 @@ Vim Snippet:
   tm_scope: source.vim-snippet
   ace_mode: text
   language_id: 81265970
+Vim9 Script:
+  type: programming
+  color: "#007030"
+  tm_scope: source.vim
+  aliases:
+  - vim9
+  - vim9script
+  extensions:
+  - ".vim"
+  - ".vim9"
+  ace_mode: text
+  language_id: 534204182
 Visual Basic .NET:
   type: programming
   color: "#945db7"
diff --git a/samples/Vim9 Script/advanced.vim b/samples/Vim9 Script/advanced.vim
new file mode 100644
index 0000000000..b92495cfb2
--- /dev/null
+++ b/samples/Vim9 Script/advanced.vim	
@@ -0,0 +1,185 @@
+vim9script noclear
+# Advanced Vim9 Script Example
+# Demonstrates modern Vim9 features for the Linguist repository
+
+# Strict typing and namespace
+import autoload 'knack.vim' as knack
+import autoload './utils.vim' as utils
+
+# Constants and typed variables
+const BUFFER_SIZE: number = 1024
+const MAX_RETRIES: number = 3
+const CONFIG_DIR: string = $HOME .. '/.config/vim'
+
+# Class definitions (Vim9 feature)
+class Cache
+  var entries: dict<any> = {}
+  var max_size: number
+
+  def new(size: number = 100)
+    this.max_size = size
+  enddef
+
+  def set(key: string, value: any): void
+    if len(this.entries) >= this.max_size
+      var first_key = keys(this.entries)[0]
+      unlet this.entries[first_key]
+    endif
+    this.entries[key] = value
+  enddef
+
+  def get(key: string): any
+    return get(this.entries, key, null)
+  enddef
+
+  def clear(): void
+    this.entries = {}
+  enddef
+endclass
+
+# Modern function syntax with type annotations
+def ProcessBuffer(buf: number, opts: dict<any>): dict<string>
+  var result: dict<string> = {}
+  var lines: list<string> = getbufline(buf, 1, '$')
+
+  # Process with early returns
+  if empty(lines)
+    result['status'] = 'empty'
+    result['count'] = '0'
+    return result
+  endif
+
+  var count: number = 0
+  for line in lines
+    if line =~# '^\s*#.*autocmd'
+      count += 1
+    endif
+  endfor
+
+  result['status'] = 'success'
+  result['count'] = string(count)
+  result['size'] = string(len(lines))
+
+  return result
+enddef
+
+# Lambda functions with strict typing
+var multiply: func(number, number): number = (a, b) => a * b
+var filter_nums: func(list<number>): list<number> =
+  (nums) => nums->filter('v:val > 10')
+
+# Object methods and method chaining
+def ApplyFormatting(content: string): string
+  return content
+    ->substitute('  ', ' ', 'g')
+    ->trim()
+    ->tolower()
+enddef
+
+# Enumerate with type safety
+def AnalyzeSettings(settings: dict<string>): list<dict<any>>
+  var results: list<dict<any>> = []
+
+  for [key, value] in items(settings)
+    var item: dict<any> = {
+      'key': key,
+      'value': value,
+      'type': typename(value),
+      'length': strlen(value)
+    }
+    results->add(item)
+  endfor
+
+  return results
+enddef
+
+# Recursive function example
+def Factorial(n: number): number
+  if n <= 1
+    return 1
+  else
+    return n * Factorial(n - 1)
+  endif
+enddef
+
+# Error handling with try-catch
+def SafeFileRead(filepath: string): list<string>
+  var lines: list<string> = []
+
+  try
+    lines = readfile(filepath)
+  catch /E484/
+    echomsg 'File not found: ' .. filepath
+    lines = []
+  catch
+    echomsg 'Error reading file: ' .. v:exception
+    lines = []
+  endtry
+
+  return lines
+enddef
+
+# Variadic function
+def JoinPaths(...parts: list<string>): string
+  return parts->join('/')
+enddef
+
+# Command definitions using new syntax
+command! -nargs=? -complete=file MyCommand {
+  var arg = <q-args>
+  var result = ProcessBuffer(bufnr(), {'name': arg})
+  echomsg 'Result: ' .. string(result)
+}
+
+# Augroup with modern syntax
+augroup MyAutocmds
+  autocmd!
+  autocmd BufWritePost *.vim {
+    var buf = expand('<abuf>')
+    echomsg 'Wrote buffer ' .. buf
+  }
+  autocmd FileType python {
+    setlocal shiftwidth=4
+    setlocal tabstop=4
+  }
+augroup END
+
+# Using the cache class
+var cache: Cache = Cache.new(50)
+cache.set('user_prefs', {'theme': 'dark', 'font_size': 12})
+
+def GetUserPrefs(): any
+  var prefs = cache.get('user_prefs')
+  if prefs == null
+    prefs = {'theme': 'light', 'font_size': 10}
+    cache.set('user_prefs', prefs)
+  endif
+  return prefs
+enddef
+
+# Advanced list comprehension patterns
+var numbers: list<number> = range(1, 100)
+var evens: list<number> = numbers->filter('v:val % 2 == 0')
+var squares: list<number> = numbers->map('v:val * v:val')
+
+# String interpolation (Vim9)
+def FormatMessage(name: string, count: number): string
+  return $'Found {count} items for {name}'
+enddef
+
+# Abort on first error (Vim9 behavior by default with vim9script)
+if !exists('g:loaded_myplugin')
+  finish
+endif
+
+g:loaded_myPlugin = 1
+
+# Export public interface
+export def PublicAPI(input: string): string
+  return 'Processed: ' .. input
+enddef
+
+# Internal helper (not exported)
+def PrivateHelper(): void
+  echomsg 'This is internal'
+enddef
diff --git a/samples/Vim9 Script/basic.vim b/samples/Vim9 Script/basic.vim
new file mode 100644
index 0000000000..2786c74840
--- /dev/null
+++ b/samples/Vim9 Script/basic.vim	
@@ -0,0 +1,57 @@
+vim9script
+
+var myNumber: number = 42
+const PI: number = 3.14159
+final myList: list<string> = ['vim', 'neovim', 'vim9']
+
+def HelloWorld(): void
+  echo "Hello, Vim9!"
+enddef
+
+def Add(a: number, b: number): number
+  return a + b
+enddef
+
+def ProcessList(items: list<string>): dict<number>
+  var result: dict<number> = {}
+  for item in items
+    result[item] = len(item)
+  endfor
+  return result
+enddef
+
+var double = (n: number): number => n * 2
+var squared = (n: number): number => n * n
+
+def CheckValue(val: number): string
+  if val > 0
+    return "positive"
+  elseif val < 0
+    return "negative"
+  else
+    return "zero"
+  endif
+enddef
+
+var name = "Vim9"
+echo $"Welcome to {name}!"
+
+export def PublicFunction(): void
+  echo "This function is exported"
+enddef
+
+def SafeDivide(a: number, b: number): number
+  try
+    return a / b
+  catch
+    echoerr "Division error"
+    return 0
+  endtry
+enddef
+
+var isEnabled: bool = true
+var isDisabled: bool = false
+
+HelloWorld()
+var sum = Add(10, 20)
+echo $"Sum: {sum}"
diff --git a/samples/Vim9 Script/copilot-chat.vim b/samples/Vim9 Script/copilot-chat.vim
new file mode 100644
index 0000000000..b12985f9dd
--- /dev/null
+++ b/samples/Vim9 Script/copilot-chat.vim	
@@ -0,0 +1,115 @@
+vim9script
+scriptencoding utf-8
+
+import autoload 'copilot_chat/auth.vim' as auth
+import autoload 'copilot_chat/buffer.vim' as _buffer
+import autoload 'copilot_chat/api.vim' as api
+
+export def OpenChat(): void
+  if _buffer.HasActiveChat() && g:copilot_reuse_active_chat == 1
+    _buffer.FocusActiveChat()
+  else
+    _buffer.Create()
+  endif
+  timer_start(10, (_) => auth.VerifySignin())
+enddef
+
+export def StartChat(message: string): void
+  OpenChat()
+  _buffer.AppendMessage(message)
+  api.AsyncRequest([{'content': message, 'role': 'user'}], [])
+enddef
+
+export def ResetChat(): void
+  if g:copilot_chat_active_buffer == -1 || !bufexists(g:copilot_chat_active_buffer)
+    echom 'No active chat window to reset'
+    return
+  endif
+
+  var current_buf = bufnr('%')
+
+  # Switch to the active chat buffer if not already there
+  if current_buf != g:copilot_chat_active_buffer
+    execute 'buffer ' .. g:copilot_chat_active_buffer
+  endif
+
+  deletebufline('%', 1, '$')
+
+  _buffer.WelcomeMessage()
+
+  if current_buf != g:copilot_chat_active_buffer && bufexists(current_buf)
+    execute 'buffer ' .. current_buf
+  endif
+enddef
+
+export def SubmitMessage(): void
+  auth.GetTokens()
+  var messages = []
+  var pattern = ' ━\+$'
+  var all_file_lists = []
+  cursor(1, 1)
+
+  while search(pattern, 'W') > 0
+    var header_line = getline('.')
+    var role = 'user'
+    # Check separator icon to determine message role
+    # Separator with  icon indicates assistant response, otherwise user message
+    if stridx(header_line, ' ') != -1
+      role = 'assistant'
+    endif
+    var start_line: number = line('.') + 1
+    var end_line: number = search(pattern, 'W')
+    if end_line == 0
+      end_line = line('$')
+    else
+      end_line -= 1
+      cursor(line('.') - 1, col('.'))
+    endif
+
+    var lines: list<string> = getline(start_line, end_line)
+    var file_list: list<string> = []
+
+    for i in range(len(lines))
+      var line: string = lines[i]
+      if line =~? '^> \(\w\+\)'
+        var text: string = matchstr(line, '^> \(\w\+\)')
+        text = substitute(text, '^> ', '', '')
+        if has_key(g:copilot_chat_prompts, text)
+          lines[i] = g:copilot_chat_prompts[text]
+        endif
+      elseif line =~? '^#file: '
+        var filename: string = matchstr(line, '^#file: \s*\zs.*\ze$')
+        add(file_list, filename)
+      endif
+    endfor
+    var message: string = join(lines, "\n")
+
+    add(messages, {'content': message, 'role': role})
+    add(all_file_lists, file_list)
+    cursor(line('.'), col('.') + 1)
+  endwhile
+
+  # Limit message history to improve performance
+  # Only send the most recent messages based on configuration
+  var limit: number = g:copilot_chat_message_history_limit
+  if len(messages) > limit && limit > 0
+    var start_idx: number = len(messages) - limit
+    messages = messages[start_idx : ]
+    all_file_lists = all_file_lists[start_idx : ]
+  endif
+
+  # Consolidate file lists from recent messages
+  # O(n) consolidation using dictionary for O(1) duplicate detection (improved from O(n²))
+  var consolidated_files: list<string> = []
+  var seen: dict<any> = {}
+  for files in all_file_lists
+    for file in files
+      if !has_key(seen, file)
+        seen[file] = 1
+        add(consolidated_files, file)
+      endif
+    endfor
+  endfor
+
+  api.AsyncRequest(messages, consolidated_files)
+enddef
diff --git a/test/fixtures/Vim Script/legacy.vim b/test/fixtures/Vim Script/legacy.vim
new file mode 100644
index 0000000000..35eede43b3
--- /dev/null
+++ b/test/fixtures/Vim Script/legacy.vim	
@@ -0,0 +1,5 @@
+let s:a = 123
+
+function s:foo()
+  return s:a
+endfunction
diff --git a/test/fixtures/Vim9 Script/vim9script.vim b/test/fixtures/Vim9 Script/vim9script.vim
new file mode 100644
index 0000000000..21b43a111b
--- /dev/null
+++ b/test/fixtures/Vim9 Script/vim9script.vim	
@@ -0,0 +1,3 @@
+vim9script noclear
+
+var a = 123
diff --git a/test/test_heuristics.rb b/test/test_heuristics.rb
index 506a2d1d7f..4025cbac8e 100755
--- a/test/test_heuristics.rb
+++ b/test/test_heuristics.rb
@@ -1179,6 +1179,13 @@ def test_vcf_by_heuristics
     })
   end
 
+  def test_vim_by_heuristics
+    assert_heuristics({
+      "Vim9 Script" => all_fixtures("Vim9 Script", "*.vim"),
+      "Vim Script" => all_fixtures("Vim Script", "*.vim")
+    })
+  end
+
   def test_w_by_heuristics
     assert_heuristics({
       "CWeb" => all_fixtures("CWeb", "*.w"),
diff --git a/vendor/README.md b/vendor/README.md
index da47065d96..1a43cf593c 100644
--- a/vendor/README.md
+++ b/vendor/README.md
@@ -664,6 +664,7 @@ This is a list of grammars that Linguist selects to provide syntax highlighting
 - **Vim Help File:** [Alhadis/language-viml](https://github.com/Alhadis/language-viml)
 - **Vim Script:** [Alhadis/language-viml](https://github.com/Alhadis/language-viml)
 - **Vim Snippet:** [Alhadis/language-viml](https://github.com/Alhadis/language-viml)
+- **Vim9 Script:** [DanBradbury/language-vim9](https://github.com/DanBradbury/language-vim9)
 - **Visual Basic .NET:** [peters-ben-0007/VBDotNetSyntax](https://github.com/peters-ben-0007/VBDotNetSyntax)
 - **Visual Basic 6.0:** [serkonda7/vscode-vba](https://github.com/serkonda7/vscode-vba)
 - **Volt:** [textmate/d.tmbundle](https://github.com/textmate/d.tmbundle)
diff --git a/vendor/grammars/language-vim9 b/vendor/grammars/language-vim9
new file mode 160000
index 0000000000..28d3207e56
--- /dev/null
+++ b/vendor/grammars/language-vim9
@@ -0,0 +1 @@
+Subproject commit 28d3207e56dc05a5e25ba92bc975b9fc3a39ca79