Blender
Invert the selection
In Blender, Ctrl + I will invert the selection. It is listed for Windows, and no Mac version is documented here.
Where it works: 3D Viewport, UV or Graph editor
Where this comes from
Default Keymap - Blender 2.80 Manual
Documentation checked on 2026-09-14. That is a documentation review, not a test run inside the application.