Gabriel Martinelli scored a brace in the first half after capitalizing on Leeds’ defensive errors, and Arsenal’s Bukayo Saka added a third before halftime.
After Joe Gelhardt was fouled by Ben White, Raphinha scored from the penalty spot for the hosts.
Arsenal are still in the top four after their triumph, while Leeds are in 16th place, five points ahead of the bottom three.
Leeds’ grueling campaign continues on Boxing Day when they travel to Liverpool. Arsenal will face Sunderland in the EFL Cup quarter-finals at the Emirates Stadium on Tuesday.
“We are together as a team and we are together with the fans, they gave us so much energy.” – Martinelli