The North End Gentry sang for a full 90 minutes, but a controversial first half penalty gave Brentford the points and promotion to the Championship.
Alan Judge converted on the half hour mark, sending Declan Rudd the wrong way and although he missed another after the break the Bees held on for the win.
Manager Simon Grayson was still without skipper John Welsh, through suspension and Joe Garner and Scott Wiseman through injury, so Alan Browne retained his place in the starting line-up and Bailey Wright returned to a back three.
It was a feisty first half, one that left the North End players and staff incensed as they went in for the break, having gone behind to the penalty just before the hour mark.
The game started slowly with on loan Blackburn midfielder Alan Judge the first with a shot in anger on nine minutes, his effort from 25 yards testing Declan Rudd, who saw it late, but pushed the ball over the bar for the first corner.
The best chance of the opening half hour fell to Craig Davies, who was denied by a last ditch tackle from James Tarkowski, after Alan Browne had played him through in a left hand channel, following a good break by Stuart Beavon. From the resulting corner, it was played short to Browne whose curling effort was cleared by Tony Craig.
The controversial moment came just before the 30 minute mark when referee Keith Hill awarded a penalty to Brentford; there was a melee in the box and the referee broke it with a shrill of the whilste, pointing to the spot, but PNE were apoplectic with anger at the awarding.
However, Alan Judge stepped up and fired into the bottom left hand corner, sending Rudd the wrong way.
The second half started with Declan Rudd at his best to deny Donaldson a second inside 90 seconds, diving low to his right to get a strong hand to the frontman’s shot in a left hand channel.
The harrying of the Brentford defence by the North End forwards brought a chance for Chris Humphrey on the hour mark; fed by Stuart Beavon, he took the ball to just outside the right hand edge of the box and fired a low shot that beat Button, but also beat the left hand post by an narrow margin.
At the mi-point in the half route one football almost saw North End level. A long ball from Declan Rudd found Alan Browne unmarked in the box, but his header was agonisingly inches wide of the left hand post from 15 yards out.
With 15 minutes left substitute Paul Gallagher won North End a corner and delivered it himself, the ball falling to Scott Laird 12 yards out. He lofted a shot over Button but it came down just over the bar onto the roof of the net rather than under it.
However, all the effort was almost undone by yet another penalty decision going against the Lilywhites! A long ball was played over the top and Bailey Wright was adjudged to have fouled Clayton Donaldson in the box, but this time Alan Judge could only find the stand and North End had a let off.
North End through everything forward in search of an equaliser, but it was not to be and the Play-Offs was the result.
Brentford line-up: Button, Craig, Douglas, Donaldson, McCormack, Dallas (Grigg, 84), Saville (Diagouraga, 86), Judge, Bidwell, Tarkowski, Trotta (Reeves, 77). Subs not used: Lee, O’Connor, Yennaris, Adams.
PNE line-up: Rudd, Clarke, King, Wright, Humphrey (K Davies, 71), Keane, Kilkenny (Gallagher, 55), Laird, Browne, Beavon, C Davies (Holmes, 54). Subs not used: Stuckmann, Huntington, Buchanan, Brownhill.
Attendance: 10,774 (1,657 away fans)
Referee: Mr K Hill