Eddie Nketiah was the hero on the night at the Emirates for the north London side.
Nketiah came off the bench to score an 85th-minute winner for Arsenal.
This came after Michail Antonio cancelled Alexander Lacazette opener.
After scoring the winner against West Ham, Nketiah addressed a recent bust-up with Dani Ceballos, who provided the assist for his goal.
“We had a bit of a coming together. The reaction was there. We made up an got on with it. It was nice for him to make the assist. It’s all love now,” Nketiah told Sky Sports post-match.
“It was a great pass across, good vision. I tried to stay onside. It was an easy finish from there.
“I want to keep improving as a player. It’s a great feeling to come on and score. West Ham made it very difficult. They came out very strongly in the second half.”