Barnsley's six-match unbeaten run lay in tatters as they gave an end of season performance against a Brentford team still battling to avoid the drop.
The home side never recovered from conceding a second minute goal and created little to cheer an Oakwell crowd of just under 10,000.
The Tykes made a series of mistakes which led to Brentford's early opener.
Both midfielder Steve Hayward and captain Peter Handyside gave the ball away and when Stuart Talbot let fly from 22 yards, Barnsley's debut keeper Ross Turnbull made a mess of his dive and the ball crept in at the far post.
Brentford were clearly up for it and the lively Jay Tabb was just off target in the seventh minute with a fierce left-foot volley.
Midfielder Ed Hutchinson also went close with a glancing header just over the bar.
Barnsley created little in the first half, apart from a shot being blocked from on-loan striker Daniel Nardiello and a Hayward free-kick which was deflected over the bar.
Brentford doubled their advantage in the 61st minute with a swift breakaway move.
Tabb left Barnsley defender Craig Ireland trailing in his wake with a surge from the halfway line and the little midfielder showed composure and clinical finishing in the way he beat Turnbull from just inside the box.
Nardiello did go close for Barnsley on 69 minutes with a low drive that brought a smart stop low down from Brentford keeper Stuart Nelson.