Arsenal continually caused chaos in the first half and Mikel Arteta's side led 3-0 at the break as a brace from Gabriel Martinelli was followed by a Bukayo Saka strike.
Leeds improved after the break and Joe Gelhardt earned the Whites a 75th-minute penalty after being fouled by Ben White, Raphinha blasting home the spot kick into the top right corner.
But Arsenal bagged a fourth goal with six minutes left when Martin Odegaard played in substitute Emile Smith Rowe who volleyed home past Illan Meslier.
Graham Smyth, the YEP's chief football writer, hands out the scores.
13. Sam Greenwood (sub)
N/A - Came on very late on but was hungry for the ball, desperate to get involved. Photo by Lewis Storey/Getty Images.
14. Liam McCarron
N/A - Another very late substitute. Had little involvement before the end. Photo by Lewis Storey/Getty Images.