With around 9,000 fans at the Emirates, the visitors more than held their own until the deadlock was broken in first-half injury-time by Theo Walcott.
Arsenal asserted their authority after the break as Olivier Giroud settled any nerves in the 53rd minute and then Luke Waterfall deflected into his own net.
Alexis Sanchez and Aaron Ramsey extended the advantage as the Gunners finished strongly to join Manchester City in the semi-finals.
