Ivory Coast international Gervinho, such a frustrating figure for the Gunners, set the hosts on their way after 11 minutes.
However, despite dominating possession, it was not until the start of the second half where the crucial breakthrough came again, this time Santi Cazorla sweeping home.
Olivier Giroud added a third following a quick break by Gervinho. Reading - who squandered a 4-0 lead against** **Arsenal in their home Capital One Cup tie earlier this season - started positively, as Mikele Leigertwood headed wide from a corner.
More top news
Thursday afternoon's weather for the west of the region
Thursday afternoon's weather for the east of the region
Thursday's weather for the west of the region