The Wales international struck his 11th league goal of the campaign mid-way through the second half to end a run of three successive draws for Andre Villas-Boas' team.
Albion played the final 42 minutes with 10 men after defender Goran Popov was sent off for spitting in the direction of Spurs defender Kyle Walker.
Tottenham took full advantage of their numerical advantage to dominate the second period despite the loss of leading scorer Jermain Defoe with an ankle injury.
Bale was a constant threat with his pace and power as he followed up his mid-week equaliser at Norwich with another crucial goal.
Popov's red card was the last thing Albion would have unwanted after all the controversy surrounding striker Peter Odemwingie's aborted move to QPR. Odemwingie was not part of Albion's matchday squad but it did not stop the Tottenham fans chanting a series of taunts aimed at the Nigeria international. But of more concern to head coach Steve Clarke will be the fact they have now won only two of their last 14 games in all competitions.
The first half chance fell to Albion after a flicked header from Lukaku, who caused problems all afternoon, found the recalled Shane Long in space with only Hugo Lloris to beat. But his first touch was heavy and forced him out wide where he eventually overran the ball which went harmlessly out of play.
Defoe, in front of England head coach Roy Hodgson, needed touchline treatment after landing awkwardly on his left ankle when avoiding a challenge from Long. But he was unable to continue and was helped down the tunnel by two Spurs physios and replaced by transfer window signing Lewis Holtby.
Albion were reduced to 10 men after only three minutes of the second half. Replays showed that Popov spat in the direction of Spurs defender Kyle Walker after the two had squared up to each other. Referee Marc Clattenburg instantly brandished a red card at the on-loan Dynamo Kiev left-back.
After 68 minutes a stunning strike from Bale put Tottenham in front. The winger, playing in a more central role, received a pass from Walker, brushed off the challenge of Brunt and his 20 yard shot flew past the despairing dive of Foster into the top corner of the net.
Source: PA
Source: PA