Goals from Adebayo Akinfenwa and Andy Robinson fired Swansea City back into the play-off zone at the Liberty Stadium.
The victory took Swansea back up to sixth and ended Gillingham's three-game winning sequence against the Swans who never looked like losing the League One encounter.
Swansea City:
Gillingham: Larrieu, Clohessey, Easton, Johnson, Chorley, Bentley, Flynn (c), Crofts, Jarvis, Mulligan, Savage. Subs: Gupp, Jackman, McDonald, Nsungu, Collin.
Ref: C Penton
Asst-refs: P V Norman, L Swabey
4th official: J H Holbrook
Att: 9,675
Swansea boss Kenny Jackett named the same starting line-up that battled out a goalless draw with Nottingham Forest on Saturday.
It meant that new signing Pawel Abbott had to be content with a place on the bench after completing his move yesterday from HuddersfieldTown.
There was also a welcome return for midfielder Darren Pratley who took his place on the bench following an ankle injury.
Marcos Painter was still out with a groin strain and Kristian O'Leary was suspended.
Gillingham, currently in 15th place, signed French goalkeeper Romain Larrieu on loan from Plymouth Argyle in time to face the Swans.
Gills manager Ronnie Jepson was forced into action after Luton exercised their right to a 24-hour recall on Dean Brill.
Ian Cox was suspended, while former Swans target Brent Sancho was out injured. Dean McDonald made his return on the bench, Duncan Jupp returned to the starting line-up after family leave.
Gillingham arrived with plenty of confidence after beating the Swans on their last three outings over the past two seasons.
Swansea made a great start after Adebayo Akinfenwa had got his eye in with a shot as early as two minutes which flew just over.
But with is sights set, Akinfenwa made no mistake five minutes later when Lee Trundle picked him out with a perfect cross from the right.
Akinfenwa lost his marker and looped a header over the head of Larrieu and into an empty net to give the Swans a 1-0 lead.
It was Akinfenwa's fifth goal of the season.
With Swansea well in control, the second nearly came in the 13th minute when the lively Butler fired a fierce shot at Larrieu which the Gills 'keeper managed to beat out. From the corner, Trundle headed Tom Williams' cross into the side netting.
Gills response came from along range shot from Bas Savage, before Trndle swept a great pass out to Butler on the left. Butler cut inside and unleashed a powerful shot which Larrieu managed to tip over with 23 minutes gone.
Williams and Ian Craney came close with two long range free-kicks before Matthew Jarvis tested Willy Gueret at the other end with a fierce shot which the Swansea 'keeper did well to push behind for a corner.
It sparked a good spell for the visitors who nearly grabbed an equalizer in the 38th minute. Clint Easton whipped in a free-kick into the six yard box which Mark Bently met with a goal-bound header, but Gueret managed to get enough on his effort to guide it past the post.
The first change of the game came in the 43rd minute, but it came in the middle with referee Clive Penton limping off to be replaced by his assistant Lee Swabey.
Half-time: Swans 1 Gills 0
Swansea created an early chance at the start of the second-half as a neat build up saw the overlapping Richard Duffy cross to the far post. But Akinfenwa just failed to get the finishing touch.
Akinfenwa had an even better chance in the 54th minute when he met a cross from Williams inside the six yard box, but the hit-man fired tamely at Larrieu when Swansea were desperate to get the second to kill the game off.
And the home side was given a timely warning in the 58th minute that the game was far from over as they let the tempo drop and Gillingham nearly grabbed an equalizer. Jarvis delivered a dangerous cross from the left and Gary Mulligan saw his header strike Gueret's bar.
Swansea were giving far too much possession away at that stage which allowed Gillingham back into the game, with Gueret having to be o his toes to save a free-kick from Mike Flynn.
In a bid to up the tempo, Jackett sent on Andy Robinson in the 65th minute for Trundle who had had a difficult night.
It nearly had the desired effect as Craney brought a good save out of Larrieu, before Andrew Croft brought an even better save out of Gueret at the other end as Swansea's play got sloppy.
Pratley came off the bench with 20 minutes remaining for Britton, before Flynn tried another long range shot which Gueret dealt with easily.
But just as the crowd were getting frustrated, Akinfenwa played in Andy Robinson on the edge of the area and the midfield drove clear to fire an unstoppable shot beyond Larrieu for Swansea's long-overdue second.
The goal gave Swansea a massive lift and they produced a great display of possession football before Bentley stemmed the tide by forcing Gueret into a fine save.
With six minutes remaining, Gillingham made a triple substitution with Savage, Bentley and Jarvis being replaced by Gupp, Collin and Nsungu.
Swansea made their final change in the 87th minute when new signing Pawel Abbott replaced Akinfenwa who was given a standing ovation.
There was just enough time for Abbott to force a save out of Larrieu and Gueret to keep a clean sheet at the other end with a fine stop from Flynn.
The three points, however, were already in the bag.
