Two goals from Lloyd Owusu enabled Brentford to keep second spot in the table and end Barnsley's six-match unbeaten run.
The Yorkshire side enjoyed a good 20 minute spell in the second half after the slightly fortunate goal but never looked like winning.
Two goals in 10 minutes capped a great first half for the home side. Brentford skipper Ricky Newman opened the scoring on 12 minutes with a delightful finish after good work from Jay Tabb.
The goal was exactly what Brentford deserved as strikers Owosu and Isaiah Rankin gave Barnsley a torrid time.
Owusu got his just reward on 23 minutes as a fine move from Brentford saw the impressive Alex Rhodes feed the striker who deftly chipped the onrushing Nick Colgan from 18 yards.
A 2-0 scoreline at the break accurately reflected the play.
Barnsley got back into things early in the second half. Busy midfielder Neil Austin was central to most things, however it took a dreadful defensive error from left-back Andy Frampton to hand the Tykes a lifeline.
Under little pressure, Frampton sliced a clearance high over his own keeper leaving Barnsley's Tommy Wright a simple two-yard tap-in.
Barnsley's fight back was cut short on 85 minutes when the referee awarded the home side a penalty following a foul by the unlucky Austin on Calum Willock.
Owusu stepped forward to grab his second high into the corner and with that the Bees continued their march towards the Championship next season.