In pouring rain, the France striker headed in the winner, but Gylfi Sigurdsson’s spectacular free-kick was the goal of the day as the club moved into fifth place.
Alexis Sanchez scored his eighth Premier League goal in 10 games to open the scoring, but surrendered the lead in a matter of minutes.
In the first half Swansea always looked the more like side to take the lead in a lively first half with Sigurdsson seeing his free-kick headed out of danger by Calum Chambers.
Chambers was in the thick of it again when Wilfried Bony went down claiming he was shoved by the Arsenal stopper, while 10 minutes before the half-time, Bony played in Marvin Emnes only for the forward to shoot straight at Wojciech Szczesny.
As the half wore on, Arsenal slowly got a foothold and some brilliant play by Danny Welbeck forced Lukasz Fabianski into making a good save at his near post. Aaron Ramsey’s sweetly struck volley then whizzed past the post moments later.
Alex Oxlade-Chamberlain came close in the first minute of the second half after nice work from Alexis Sanchez, but he could not get enough power in his shot.
With an hour gone, it was Oxlade-Chamberlain again in the thick of it.
The 21-year-old picked up the ball in the middle and darted through the Swans’ defence where Santi Cazorla continued the attack, finding Welbeck on the right, whose low pass across the 18-yard box found Sanchez unmarked and it was an easy finish for the Chile international.
However, Kieran Gibbs later presented the home side with the perfect chance to equalise when he brought down Modou Barrow 30 yards out.
Sigurdsson stood over it and curled it into Szczesny’s top corner and Arsenal had barely got the game back underway when Gomis powered Swansea in front.
Jefferson Montero, not for the first time in the match, skinned Chambers and Gomis, on for Bony just minutes earlier, rose highest to head in the Ecuador winger’s cross.
Arsenal manager Arsene Wenger took off Mathieu Flamini and Ramsey and threw on Theo Walcott and Jack Wilshere for the final ten minutes, but nothing happened and the Liberty was rocking when the full-time whistle sounded.
In other results:
|FT||Sunderland||1 – 1|
|FT||Tottenham Hotspur||1 – 2|
|FT||West Bromwich Albion||0 – 2||Newcastle United|