How to cancel Finder search via keyboard?

It depends on your locale and how you started the search:

  • If you started the search with no window open, it's simply W (which closes the window)
  • If you started the search in an open window, it's [ (US)(or e.g. Ö (German)) which goes one step back to the previous window. The shortcut is usually visible in the menubar of the Finder > Go > Back.