Leeds impressed in the first half but substitute Calum Chambers put Arsenal ahead with a header from a corner in the 55th minute, netting with his first touch of the game and 23 seconds after his introduction for the injured Ben White.
After a header from captain Liam Cooper to goalkeeper Illan Meslier fell short, former Whites loanee Eddie Nketiah then doubled Arsenal's lead in the 69th minute.
Graham Smyth, the YEP's chief football writer, hands out the scores as Leeds squandered an opportunity to book a place in the quarter-finals.
13. Joe Gelhardt (sub)
6 - Willing, hard working, got stuck in but couldn't provide a spark like he did against Wolves. Picture by Bruce Rollinson.
14. Liam Cooper (sub)
5 - At fault for Nketiah's goal. Tried to make amends with front foot defending with some success. Picture by Bruce Rollinson.
15. Crysencio Summerville (sub)
5 - Another for whom it was difficult to make an impact due to the events before his introduction. Picture by Bruce Rollinson.
16. Sam Greenwood (sub)
5 - Game felt like it had gone by the time he arrived. Tried to get on the ball against his old club. Picture by Bruce Rollinson.
17. Andre Marriner (referee)
6 - A little fussy at times, didn't let things flow as well as he might have. No real controversy to deal with. Photo by Rui Vieira - Pool/Getty Images.