From GNOME settings GUI, you can only add keyboard shortcuts for up to 4 workspaces.

If your workflow depends on more than 4 workspaces, you cannot add them via gnome-control-center aka GNOME Settings GUI.

There are two methods to add shortcuts for up-to 12 workspaces.

dconf Editor

Open the dconf Editor, accept the risk associated with changing default settings via dconf Editor

Then navigate to: org > gnome >desktop > wm > keybindings

Or click on search 🔎 icon, and put this in the search bar:

/org/gnome/desktop/wm/keybindings/

1. Click on switch-to-workspace-5 (not available via gnome-control-center)

2. Turn off Use default value

3. Add your Custom value for key binding, i.e. Super + 5

['<Super><Shift>5']

Then go back to /org/gnome/desktop/wm/keybindings/ and click on move-to-workspace-5.

Using the previous steps, add this shortcut Super + Shift + 5 (To move focused app to workspace-5) to Custom value field.

['<Super><Shift>5']

Terminal: Using gsettings (Recommended)

The more direct and easy method is using gsettings via terminal. This command is available on GNOME desktop by default.

• To assign a shortcut to switch to workspace#6 (Just an example you select any number up-to 12)

1

gsettings set  org.gnome.desktop.wm.keybindings switch-to-workspace-6 "['<Super>6']"

Then you can use Super +6 to switch to workspace#6.

• If you also want a shortcut to send apps to workspace#6, run in the terminal

gsettings set  org.gnome.desktop.wm.keybindings move-to-workspace-6 "['<Super><Shift>6']"

Now you can use Super + Shift + 6 key binding to move a focused app to workspace#6.