Harry Cornick came off the bench to score the only goal of the game against Swansea and lift Luton to within three points of the Sky Bet Championship play-off places.
The striker scored his first goal for three months, and eighth of the season, to leave sliding Swansea with just one win in their last seven games.
By contrast, Luton have won four of their last seven.
Swansea had given a debut to goalkeeper Andy Fisher, a £400,000 signing from MK Dons during the transfer window, but failed to give him a reassuring welcome.
Not only did the home defence play their team-mate into deep trouble so that he was forced to scramble the ball clear inside two minutes but their mistakes continued to put him under pressure.
A free-kick conceded led to Luton striker Danny Hylton glancing the ball just wide from James Bree’s delivery before Amari’i Bell’s cross was almost turned in by Allan Campbell.
Swansea eventually settled and with Matt Grimes prompting them from midfield, they began to create their own opportunities.
A rapid counter-attack ended with a shot from Olivier Ntcham being blocked in the goalmouth, while Grimes continued to create openings for team-mates, including Hannes Wolf, the loan signing from RB Leipzig.
But it was Luton who again came closest to scoring just before the break when another set-piece from Bree was headed just over by Hylton, before Reece Burke’s curling shot flew wide.
Swansea had most of the ball but they lacked a focal point, especially with top scorer Joel Piroe left on the bench after a recent heavy workload.
It was not until the 55th minute that they posed a real threat to James Shea in the Luton goal.
But when Ben Cabango met Wolf’s cross with a firm header, the ball came back off the far post and Ryan Bennett was unable to force home the rebound.
Luton and their Welsh manager Nathan Jones made a double substitution just past the hour mark when they sent on Cornick and Cameron Jerome for Hylton and Fred Onyedinma, but most of the pressure was now being exerted by the home side.
They threatened again with 20 minutes remaining when Wolf’s pace and trickery presented a chance for Michael Obafemi, but the striker’s effort was blocked.
As Swansea pushed forward, they began to leave more space at the back and they were made to pay by Cornick in the 72nd minute.
The striker found space on the right hand side of the penalty area and whipped a fierce shot across Fisher and inside the far post.
Luton had relatively few scares in holding onto their lead in the final few minutes as Swansea struggled to create openings.
The closest they came was a header by substitute Piroe which was saved by Shea.
