How to Assign an App to a Specific Desktop on Mac

If you keep Mail on desktop 2 and your editor on desktop 1, macOS can enforce that for you. A hidden setting in each app's Dock menu pins the app to one Space — or puts it on every Space at once. It's three clicks, and almost nobody knows it exists.

Assign an app to one desktop

The crucial detail: the assignment is "whatever Space you're on when you set it." So position yourself first.

1. Switch to the desktop where you want the app to live — swipe with three or four fingers, press Ctrl+←/→, or pick it in Mission Control.
2. Right-click the app's icon in the Dock (the app should be running or pinned).
3. Hover over Options.
4. Under Assign To, choose This Desktop.

From now on the app opens on that desktop, and clicking its Dock icon whisks you over to it instead of opening windows wherever you happen to be. It's the cleanest cure for windows that scatter across Spaces.

Put an app on every desktop

The same menu has the opposite trick. Choose Options → Assign To → All Desktops and the app's windows follow you to every Space — always there, no switching. It suits reference-style apps: Notes, Music, a chat window, a timer. (This is different from "keep this window floating on top" — the window travels with you but stacks normally with other windows.)

Undo it: back to None

To release an app from its assignment, right-click its Dock icon and choose Options → Assign To → None. The app goes back to default behavior: new windows open on whichever Space is active. The three choices — All Desktops, This Desktop, None — are radio buttons; the current one shows a checkmark, so you can always see what's set.

Multiple monitors and other fine print

• With more than one display (and Displays have separate Spaces enabled in Mission Control settings), the menu offers per-display options such as Desktop on Display 1 and Desktop on Display 2 — so you can pin Slack to the side monitor permanently.
• Assignments stick per app, survive restarts, and live outside System Settings entirely — the Dock menu is the only UI for them.
• If a desktop with assigned apps is deleted (drag it away in Mission Control), its apps quietly fall back to no assignment.
• Windows still jumping Spaces on their own? That's usually a different Mission Control setting — see stopping apps from switching Spaces.

New to multiple desktops?

Space assignments make the most sense once you have two or three desktops with real jobs — comms, code, browsing. If you haven't set that up yet, start with our guide to multiple desktops on Mac.