Sam Kasiano looked to have given the Bulldogs the lead when he charged to the line, but the big New Zealander was adjudged to have impeded two players and the try was ruled out by the video referee.
To add insult to injury for the visitors, the Roosters responded when Anthony Minichiello darted over and Braith Anasta added the extras.
However, the Bulldogs scored two quick tries just before the interval with Inu brilliantly catching and offloading in mid-air for Frank Pritchard to crash over.
And from the following set, Jonathan Wright latched onto Michael Ennis's hopeful kick forward and touched down.
The Roosters started the second half well but the Bulldogs took control by the 56th minute with Inu darting over from dummy-half for his second four-pointer.
David Stagg then touched down for his side's fourth try just after the hour-mark, and Wright iced the game with a breakaway run from 90 metres after Anasta's intended pass for Mitch Aubusson fell into his hands.
- AAP