The 22-year-old, who is out of contract this summer, put Arsenal ahead early before Timo Werner’s deflected strike quickly returned level with the Blues. Emile Smith Rowe restored the visitors’ lead but once again they were pushed back, this time Cesar Azpilicueta the man to put Chelsea on his terms.
There was to be no third equalizer after Nketiah put his side in front after the break, and the Gunners sealed a massive three points when Bukayo Saka scored from the penalty spot in stoppage time.
After bouncing back from three straight defeats, Mikel Arteta’s side are now level on points with Tottenham heading into the final six games of the season.
Romelu Lukaku started for the first time in two months for Chelsea, while Arsenal brought in Rob Holding and Mohamed Elneny as they looked to bring some strength back to the side.
Solidity is not a word that can be used to describe the frenetic first half that followed.
It was a slow start from the Gunners but they took the lead early on thanks to a gift from their hosts. Andreas Christensen played a terrible backpass, Nketiah jumped on it and finished with consummate ease past Edouard Mendy as he finally pulled away from the mark in the league.
Five minutes later, however, Chelsea were level. Arsenal lost it deep in their own half this time, allowing Werner to cut inside and his shot, with the help of a big deflection from Granit Xhaka, beat Aaron Ramsdale at his near post.
Saka had more and more joy on the right wing, seemingly beating Marcos Alonso at will, and he was involved as the Gunners restored their lead. He drifted inside and found Martin Odegaard, he played him to Smith Rowe who sent a wonderful first time into the far corner.
Once again five minutes was all Arsenal managed before they were pushed back. Ben White thought he had been fouled, but the referee waved play as Mason Mount curled a low cross into the box, and Azpilicueta was there to push his side level.
The visitors could well have had a third before the break as Smith Rowe came close after brilliantly finding space after a crazy first 45 minutes.
Thiago Silva was introduced at half-time, as Thomas Tuchel tried to calm the debates.
It worked for the early stages of the second half, but then Arsenal took the lead for a third time in incredibly disjointed fashion. As Nketiah looked to turn into space, Silva brushed the ball away and it bounced off Malang Sarr and back into the striker’s path. The ball bounced again, before Nketiah had just about enough at the end to beat Mendy.
Chelsea nearly equalized a third, as Alonso’s deflected strike flew to the far corner, but White came back to clear it off the line.
Gabriel Martinelli and Cedric Soares, both introduced on the bench, had chances to make more dangerous counterattacks but couldn’t find a final ball that would have ended the game.
The victory was sealed, however, as Azpilicueta pushed Saka into the box and the referee pointed the spot. Saka rose and sent the penalty to seal a famous victory, as the Gunners kept their fate in the top four in their hands.