The Wales international struck his 11th league goal of the campaign midway 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 midweek equaliser at Norwich with another crucial goal, slamming an unstoppable 20-yard drive home.
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.