If you use a MacBook connected to a massive 27-inch external monitor, macOS’s default multi-display behavior can be incredibly annoying. By default, if you move your mouse to the bottom of the external monitor, the macOS Dock will suddenly teleport away from your MacBook screen and pop up on your external display, obscuring the bottom of your active windows.
While you can go to System Settings and completely enable “Automatically hide and show the Dock,” this applies to all screens. What if you want the Dock to be permanently visible and locked to your MacBook’s built-in screen, but completely disabled on your external monitor so it never accidentally pops up while you are working?
macOS does not offer a toggle switch for this specific configuration, but you can achieve it by manipulating how the operating system handles “Spaces” (virtual desktops).
Step 1: Open System Settings
- Click the Apple logo in the extreme top-left corner of your screen.
- Select System Settings (or “System Preferences” on older macOS versions).
Step 2: Navigate to Desktop & Dock
- Scroll down the left-hand sidebar until you find Desktop & Dock. Click on it.
- Scroll down the main right-hand window until you find the section labeled Mission Control (usually located near the bottom).
Step 3: Disable Separate Spaces
The reason the Dock is able to teleport between screens is because macOS treats every single monitor as a completely independent “Space” with its own dedicated menu bar and Dock access.
- Look for the toggle switch labeled Displays have separate Spaces.
- By default, this switch is turned On (blue).
- Click the switch to turn it Off (grey).
Step 4: Reboot to Apply the Core Change
Because Spaces are tied directly to the core window manager (WindowServer), this change cannot happen live.
- A small prompt will appear telling you that you must log out for the change to take effect.
- Save any open work, click the Apple logo, and select Log Out (or simply restart your Mac entirely).
The Result
When you log back into your Mac, the multi-monitor paradigm has fundamentally shifted. macOS now treats your MacBook screen and your external monitor as one giant, contiguous canvas.
Because they are no longer treated as independent zones, the Dock is permanently anchored to your primary display (which is usually your MacBook screen). You can aggressively move your mouse to the absolute bottom edge of your external monitor, and the Dock will absolutely refuse to appear. You have successfully locked the Dock to one screen while maximizing the uninterrupted real estate of your external display.