diff --git a/src/openai/cli/_cli.py b/src/openai/cli/_cli.py
index d31196da50..18e0e84bd4 100644
--- a/src/openai/cli/_cli.py
+++ b/src/openai/cli/_cli.py
@@ -19,6 +19,7 @@
 from .._compat import PYDANTIC_V1, ConfigDict, model_parse
 from .._models import BaseModel
 from .._exceptions import APIError
+from ._completion import register_completion_command
 
 logger = logging.getLogger()
 formatter = logging.Formatter("[%(asctime)s] %(message)s")
@@ -107,7 +108,7 @@ def _build_parser() -> argparse.ArgumentParser:
         version="%(prog)s " + __version__,
     )
 
-    def help() -> None:
+    def help(args: argparse.Namespace | None = None) -> None:
         parser.print_help()
 
     parser.set_defaults(func=help)
@@ -120,6 +121,9 @@ def help() -> None:
     sub_tools = subparsers.add_parser("tools", help="Client side tools for convenience")
     _tools.register_commands(sub_tools, subparsers)
 
+    # Register the completion subcommand
+    register_completion_command(subparsers)
+
     return parser
 
 
@@ -221,7 +225,7 @@ def _main() -> None:
                 )
             )
         else:
-            parsed.func()
+            parsed.func(parsed)
     finally:
         try:
             http_client.close()
diff --git a/src/openai/cli/_completion.py b/src/openai/cli/_completion.py
new file mode 100644
index 0000000000..eb85310f3d
--- /dev/null
+++ b/src/openai/cli/_completion.py
@@ -0,0 +1,273 @@
+"""Shell completion script generator for OpenAI CLI.
+
+Generates completion scripts for bash, zsh, fish, and PowerShell.
+Usage: openai completion <shell>
+
+Author: Ahmed Adel Bakr Alderai
+"""
+
+from __future__ import annotations
+
+import sys
+import argparse
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    pass
+
+
+BASH_COMPLETION = '''# OpenAI CLI Bash Completion
+# Add to ~/.bashrc: eval "$(openai completion bash)"
+
+_openai_completions() {
+    local cur prev words cword
+    _init_completion || return
+
+    local commands="api tools completion"
+    local api_commands="chat.completions.create models.list models.retrieve files.create files.list files.retrieve files.delete files.content audio.transcriptions.create audio.translations.create images.generate images.edit images.create_variation embeddings.create moderations.create"
+    local tools_commands="fine_tunes.prepare_data"
+    local global_opts="-v --verbose -b --api-base -k --api-key -p --proxy -o --organization -t --api-type --api-version --azure-endpoint --azure-ad-token -V --version -h --help"
+
+    case "${prev}" in
+        openai)
+            COMPREPLY=($(compgen -W "${commands} ${global_opts}" -- "${cur}"))
+            return 0
+            ;;
+        api)
+            COMPREPLY=($(compgen -W "${api_commands}" -- "${cur}"))
+            return 0
+            ;;
+        tools)
+            COMPREPLY=($(compgen -W "${tools_commands}" -- "${cur}"))
+            return 0
+            ;;
+        completion)
+            COMPREPLY=($(compgen -W "bash zsh fish powershell" -- "${cur}"))
+            return 0
+            ;;
+        -t|--api-type)
+            COMPREPLY=($(compgen -W "openai azure" -- "${cur}"))
+            return 0
+            ;;
+        -k|--api-key|-b|--api-base|-o|--organization|--api-version|--azure-endpoint|--azure-ad-token|-p|--proxy)
+            # These require user input, no completion
+            return 0
+            ;;
+    esac
+
+    if [[ "${cur}" == -* ]]; then
+        COMPREPLY=($(compgen -W "${global_opts}" -- "${cur}"))
+        return 0
+    fi
+
+    COMPREPLY=($(compgen -W "${commands}" -- "${cur}"))
+}
+
+complete -F _openai_completions openai
+'''
+
+ZSH_COMPLETION = '''#compdef openai
+# OpenAI CLI Zsh Completion
+# Add to ~/.zshrc: eval "$(openai completion zsh)"
+
+_openai() {
+    local -a commands api_commands tools_commands shells
+
+    commands=(
+        'api:Direct API calls'
+        'tools:Client side tools for convenience'
+        'completion:Generate shell completion scripts'
+    )
+
+    api_commands=(
+        'chat.completions.create:Create a chat completion'
+        'models.list:List available models'
+        'models.retrieve:Retrieve a model'
+        'files.create:Upload a file'
+        'files.list:List files'
+        'files.retrieve:Retrieve a file'
+        'files.delete:Delete a file'
+        'files.content:Get file content'
+        'audio.transcriptions.create:Transcribe audio'
+        'audio.translations.create:Translate audio'
+        'images.generate:Generate images'
+        'images.edit:Edit images'
+        'images.create_variation:Create image variations'
+        'embeddings.create:Create embeddings'
+        'moderations.create:Create moderation'
+    )
+
+    tools_commands=(
+        'fine_tunes.prepare_data:Prepare data for fine-tuning'
+    )
+
+    shells=(
+        'bash:Generate Bash completion script'
+        'zsh:Generate Zsh completion script'
+        'fish:Generate Fish completion script'
+        'powershell:Generate PowerShell completion script'
+    )
+
+    _arguments -C \\
+        '-v[Set verbosity]' \\
+        '--verbose[Set verbosity]' \\
+        '-b[API base URL]:url:' \\
+        '--api-base[API base URL]:url:' \\
+        '-k[API key]:key:' \\
+        '--api-key[API key]:key:' \\
+        '-p[Proxy URL]:proxy:' \\
+        '--proxy[Proxy URL]:proxy:' \\
+        '-o[Organization]:org:' \\
+        '--organization[Organization]:org:' \\
+        '-t[API type]:type:(openai azure)' \\
+        '--api-type[API type]:type:(openai azure)' \\
+        '--api-version[Azure API version]:version:' \\
+        '--azure-endpoint[Azure endpoint]:endpoint:' \\
+        '--azure-ad-token[Azure AD token]:token:' \\
+        '-V[Show version]' \\
+        '--version[Show version]' \\
+        '1: :->command' \\
+        '2: :->subcommand' \\
+        '*::arg:->args'
+
+    case "$state" in
+        command)
+            _describe -t commands 'openai commands' commands
+            ;;
+        subcommand)
+            case "$words[2]" in
+                api)
+                    _describe -t api_commands 'api commands' api_commands
+                    ;;
+                tools)
+                    _describe -t tools_commands 'tools commands' tools_commands
+                    ;;
+                completion)
+                    _describe -t shells 'shells' shells
+                    ;;
+            esac
+            ;;
+    esac
+}
+
+_openai "$@"
+'''
+
+FISH_COMPLETION = '''# OpenAI CLI Fish Completion
+# Save to ~/.config/fish/completions/openai.fish
+
+# Disable file completion by default
+complete -c openai -f
+
+# Global options
+complete -c openai -s v -l verbose -d "Set verbosity"
+complete -c openai -s b -l api-base -d "API base URL" -r
+complete -c openai -s k -l api-key -d "API key" -r
+complete -c openai -s p -l proxy -d "Proxy URL" -r
+complete -c openai -s o -l organization -d "Organization" -r
+complete -c openai -s t -l api-type -d "API type" -ra "openai azure"
+complete -c openai -l api-version -d "Azure API version" -r
+complete -c openai -l azure-endpoint -d "Azure endpoint" -r
+complete -c openai -l azure-ad-token -d "Azure AD token" -r
+complete -c openai -s V -l version -d "Show version"
+complete -c openai -s h -l help -d "Show help"
+
+# Main commands
+complete -c openai -n "__fish_use_subcommand" -a "api" -d "Direct API calls"
+complete -c openai -n "__fish_use_subcommand" -a "tools" -d "Client side tools"
+complete -c openai -n "__fish_use_subcommand" -a "completion" -d "Generate shell completion"
+
+# API subcommands
+complete -c openai -n "__fish_seen_subcommand_from api" -a "chat.completions.create" -d "Create chat completion"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "models.list" -d "List models"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "models.retrieve" -d "Retrieve model"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "files.create" -d "Upload file"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "files.list" -d "List files"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "files.retrieve" -d "Retrieve file"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "files.delete" -d "Delete file"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "files.content" -d "Get file content"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "audio.transcriptions.create" -d "Transcribe audio"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "audio.translations.create" -d "Translate audio"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "images.generate" -d "Generate images"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "images.edit" -d "Edit images"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "images.create_variation" -d "Create variations"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "embeddings.create" -d "Create embeddings"
+complete -c openai -n "__fish_seen_subcommand_from api" -a "moderations.create" -d "Create moderation"
+
+# Tools subcommands
+complete -c openai -n "__fish_seen_subcommand_from tools" -a "fine_tunes.prepare_data" -d "Prepare fine-tuning data"
+
+# Completion subcommands
+complete -c openai -n "__fish_seen_subcommand_from completion" -a "bash" -d "Bash completion"
+complete -c openai -n "__fish_seen_subcommand_from completion" -a "zsh" -d "Zsh completion"
+complete -c openai -n "__fish_seen_subcommand_from completion" -a "fish" -d "Fish completion"
+complete -c openai -n "__fish_seen_subcommand_from completion" -a "powershell" -d "PowerShell completion"
+'''
+
+POWERSHELL_COMPLETION = '''# OpenAI CLI PowerShell Completion
+# Add to $PROFILE: . (openai completion powershell | Out-String)
+
+Register-ArgumentCompleter -Native -CommandName openai -ScriptBlock {
+    param($wordToComplete, $commandAst, $cursorPosition)
+
+    $commands = @{
+        'openai' = @('api', 'tools', 'completion', '-v', '--verbose', '-b', '--api-base', '-k', '--api-key', '-p', '--proxy', '-o', '--organization', '-t', '--api-type', '--api-version', '--azure-endpoint', '--azure-ad-token', '-V', '--version', '-h', '--help')
+        'api' = @('chat.completions.create', 'models.list', 'models.retrieve', 'files.create', 'files.list', 'files.retrieve', 'files.delete', 'files.content', 'audio.transcriptions.create', 'audio.translations.create', 'images.generate', 'images.edit', 'images.create_variation', 'embeddings.create', 'moderations.create')
+        'tools' = @('fine_tunes.prepare_data')
+        'completion' = @('bash', 'zsh', 'fish', 'powershell')
+    }
+
+    $elements = $commandAst.CommandElements
+    $command = 'openai'
+
+    for ($i = 1; $i -lt $elements.Count; $i++) {
+        $element = $elements[$i].Extent.Text
+        if ($commands.ContainsKey($element)) {
+            $command = $element
+        }
+    }
+
+    $completions = $commands[$command]
+
+    $completions | Where-Object { $_ -like "$wordToComplete*" } | ForEach-Object {
+        [System.Management.Automation.CompletionResult]::new($_, $_, 'ParameterValue', $_)
+    }
+}
+'''
+
+
+def get_completion_script(shell: str) -> str:
+    """Get the completion script for the specified shell."""
+    scripts = {
+        "bash": BASH_COMPLETION,
+        "zsh": ZSH_COMPLETION,
+        "fish": FISH_COMPLETION,
+        "powershell": POWERSHELL_COMPLETION,
+    }
+
+    if shell not in scripts:
+        raise ValueError(f"Unsupported shell: {shell}. Supported: {', '.join(scripts.keys())}")
+
+    return scripts[shell]
+
+
+def completion_command(args: argparse.Namespace) -> None:
+    """Handle the completion subcommand."""
+    script = get_completion_script(args.shell)
+    sys.stdout.write(script)
+
+
+def register_completion_command(subparsers: argparse._SubParsersAction) -> None:
+    """Register the completion subcommand."""
+    parser = subparsers.add_parser(
+        "completion",
+        help="Generate shell completion scripts",
+        description="Generate shell completion scripts for bash, zsh, fish, or powershell.",
+    )
+    parser.add_argument(
+        "shell",
+        choices=["bash", "zsh", "fish", "powershell"],
+        help="The shell to generate completion for",
+    )
+
+    parser.set_defaults(func=completion_command)