The league leaders were far too good for their mid-table opponents and could have recorded a more comfortable win.
They dominated midfield and Accrington's cumbersome defence could find no way to stop the powerful Sam Williams and the wily Billy Clarke.
The home side were ahead within eight minutes when Williams headed a long ball from Karleigh Osborne over Kenny Arthur from 12 yards.
Although Brentford were well on top it took them until the latter stages of the half to get the second goal they deserve.
Clarke set it up with a cross-field pass to Sam Wood which was worked inside to Ryan Dickson, who scored his first Brentford goal from close range.
David Hunt fired a free-kick narrowly wide as Brentford sought to turn their possession into goals and early in the second half they had a third.
A penalty was awarded when Williams was brought down by Kieran Charnock and Clarke stepped up to slot home.
Brentford could have handed Accrington a thrashing if it wasn't for Arthur and some wasteful finishing.
Clarke forced a fine low save from the Accrington shot-stopper with a header and then saw a lofted cross-cum-shot fly inches wide.
Arthur denied the nippy striker minutes later and Adam Newton clipped the outside of a post after a Williams knock down.
Robbie Williams should have pulled one back but he headed straight at Ben Hamer from six yards and John Mullin shot narrowly over from 20 yards.
The results Brentford needed to go their way in order to go up did not materialise, but they now need just three points from their last three games to clinch promotion.