Goals on the break from James Henry and a Michael Jacobs brace sealed the points for smash-and-grab Wanderers.
Brentford dominated possession throughout but failed to turn it into any clear-cut chances.
Henry broke the deadlock on the stroke of half-time, looping a speculative effort over flat-footed Bees goalkeeper David Button.
Nouha Dicko split the home defence with a superb pass in the 72nd minute to send Jacobs clear to toe poke home.
And the win was complete with minutes remaining when Scott Goldbourne twisted his way to the byline for Jacobs to curl home a fine second from the edge of the box.
The closest Brentford came in a game of few chances was Alan Judge’s free-kick on the hour-mark, which was palmed wide by Carl Ikeme.
Brentford were more direct in the dying minutes and it almost paid off when the ball dropped kindly for Jonathan Douglas, but his lashed drive was tipped wide by Ikeme.