Arsenal fans will now focus their attention on the game between Liverpool and second-placed Manchester City on Sunday.
The final whistle confirmed Arsenal’s dominance as they remain top of the Premier League standings.
The result marked United’s 15th league defeat of the season.
Kai Havertz then made sure of the victory that lifted Arsenal to the level with leaders Manchester City at 14 points.
Leandro Trossard gave Arsenal the lead 20 minutes into the game.
The English side beat the Portuguese giants in a penalty shootout after playing 1-1 on aggregate.
A few minutes before halftime, Saka, from the penalty spot, doubled Arsenal’s lead before scoring his second in the game.
The Gunners broke through West Ham defence, netting four of their six goals within 15 minutes.
Zinchenko made it 3-1 with an improvised volley after Burnley failed to clear a corner.
Arsenal made late attempts to probably steal a comeback win, but Chelsea were able to absorb the late pressure.
