Injury and a lack of match fitness had kept Bale largely on the sidelines since rejoining Spurs on loan from Real Madrid in September.
But the man who left Tottenham to head to the Spanish capital for a world record fee in 2013 showed he retains an eye for goal with a powerful header from Sergio Reguilon’s cross 18 minutes from time.
The Welshman’s intervention also served to lessen the furore over Brighton’s equaliser, scored by Tariq Lamptey, in a match dogged by controversial refereeing decisions.
Pierre-Emile Hojbjerg looked to have been clearly fouled by Solly March before the ball was worked to Lamptey, who produced a clinical finish into the far corner for his first goal for the club.
However, referee Graham Scott stood by his original decision not to award a Tottenham free-kick after reviewing the incident on the pitchside monitor.
That balanced up the dubious calls as Spurs led at half-time thanks to Harry Kane’s first-half penalty, while Brighton were denied a spot-kick.
Kane was bundled over by former England teammate Adam Lallana, but after Scott initially awarded a free-kick on the edge of the box, he was instructed by VAR that the foul took place inside the box.
There was less doubt over the result of the spot-kick as the in-form Kane coolly dispatched his 199th Tottenham goal.
It was a familiar story for Brighton as their winless run stretched to six games despite going on to enjoy the better of the game for long spells.
Graham Potter could not believe his luck when a pull on Leandro Trossard by Matt Doherty was not punished with a penalty at the other end.
A further two Tottenham penalty appeals were waved away early in the second-half as Kane and Son Heung-min went to ground easily.
Mourinho was then left cursing the officiating as for the first time in the Premier League this season a referee stood by his inital call after seeing replays of an incident for the Brighton equaliser.
Erik Lamela fired a long-range effort off the post as Spurs were suddenly jolted into looking for a winner.
The Argentine was replaced by Bale 20 minutes from time and the substitute took just three minutes to make his impact when he met his former Madrid teammate Reguilon’s inch-perfect cross.
Spurs could have been top of the table had they not thrown away four points in the dying seconds of their last two home league games against Newcastle and West Ham.
However, this time they held out to move within two points of Liverpool at the summit.