Spurs had not even scored - never mind won - on their five previous trips to St Mary's but dominated the first half on the south coast.
Bale gave the north Londoners the lead just 15 minutes into the match against the club with whom he began his career, heading home on his return to action following the birth of his first child.
Spurs deservedly doubled their advantage as half-time approached through Clint Dempsey, who directed home into an empty net after Jose Fonte's clearance off the line fell straight into his path.
A vastly-improved Saints side re-emerged for the second period and they reduced the deficit in the 66th minute when Jay Rodriguez lashed home his first Premier League goal.
Southampton continued to press for a leveller as the clock wound down but could not find an elusive second goal, much to the frustration of under-pressure manager Nigel Adkins.
The hosts came into the game with just one win to their name since their return to the top flight, although things could have been a lot different had they not conceded 24 goals already this campaign.
That defensive shakiness was evident after just three minutes when Aaron Lennon prodded wide after a Jan Vertonghen cross caused confusion at the back.
It was a quiet opening at St Mary's but one in which Spurs looked the more threatening.
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Jermain Defoe came agonisingly close to giving Tottenham a 14th-minute lead after connecting with a Kyle Walker cutback and a minute later Southampton's defence was breached by a familiar face.
Tom Huddlestone clipped an excellent weighted ball into the box and Bale met the ball with gusto to arrow a header past Artur Boruc.
The winger kept his celebrations to a minimum in respect to his former employers, who he almost punished again with a driven cross that Danny Fox had to turn behind.
Bale then headed over and Defoe blazed over as Tottenham continued to search for a second.
Southampton, by comparison, were looking devoid of ideas going forward and were unable to get away a shot in the first half.
The first period was made all the worse for Saints six minutes before the break as Lennon ran at the defence and played through Defoe.
The England international's effort was cleared off the line by the stumbling Fonte but straight into the path of Dempsey to bundle home, before an exchange between Boruc and home fans capped a miserable first half for the hosts.
Saints looked rejuvenated when play resumed, with Jason Puncheon putting an acrobatic effort just wide soon after the restart.
Fox then fired a long-range effort over for the home side, who were fortunate not to concede another when Walker burst through on goal only to screw wide.
Huddlestone was the next to put wide for Spurs, before Adkins brought on Emmanuel Mayuka in a bid to claw their way back.
Rodriguez nodded wide shortly afterwards and Maya Yoshida saw a header blocked behind from a free-kick.
Saints were looking more like the attacking threat they had shown in previous games and reduced the deficit in the 66th minute.
Brad Friedel did excellently to stop Fonte's goal-bound flick from Fox's corner, but could do nothing to prevent Rodriguez smashing in the rebound.
The former Burnley striker came close to doubling his tally three minutes later with a half volley, before William Gallas did well to deflect a Rickie Lambert shot behind.
The Spurs captain had to be alert to clear a Adam Lallana cross out of danger as Saints upped the ante.
Rodriguez fired wide from 20 yards as the home side pushed for a leveller, with substitute Guly do Prado and Morgan Schneiderlin seeing late efforts blocked as Spurs held out for three points.