Spurs looked like they were going to blow a golden opportunity to leapfrog city rivals Arsenal into fourth place until the Welshman popped up in the 86th minute to save the day.
The Saints were the better side throughout much of the contest and will feel slightly aggrieved that they did not leave north London with a point in tow.
Spurs came into the contest two points behind the Gunners in the race for the final Champions League spot but inexplicably looked disinterested for large portions of the match.
Southampton made a bright start and had an excellent chance to open the scoring in the 10th minute.
Nathaniel Clyne was played in behind the Tottenham defence only to send his effort inches wide of the post with only goalkeeper Hugo Lloris to beat.
The Saints then fired another warning shot when Rickie Lambert redirected a cross that Lloris did well to tip off the post before Jos Hooiveld’s follow-up was headed away.
Southampton was the better team in the first 45 minutes and was unlucky not to have a lead heading into the half-time break.
The visitors controlled most of the play in the first 15 minutes of the second half with Adam Lallana unable to convert on a couple of occasions.
Tottenham woke up from its slumber briefly when Clint Dempsey found himself some space but his shot failed to trouble Artur Boruc in the Southampton goal.
The White Hart Lane faithful started to urge their team on in the final 15 minutes but the lack of urgency from Spurs was puzzling.
Then Bale took center stage as he has done so many times this season to rescue the home side. The 23 year old cut inside and unleashed a shot that found the corner to send the Spurs faithful into raptures.
Gareth Bale scored another huge goal for Tottenham and showed once again why he is one of the most coveted players in Europe.