After consecutive 0-0 draws since Benitez replaced crowd favourite Roberto Di Matteo the European champions at least found the net courtesy of Juan Mata's 13th-minute strike.
However, West Ham responded after the break with Carlton Cole equalising against his former club just past the hour mark and substitute Mohamed Diame firing the home side ahead after 86 minutes to send the Upton Park crowd wild.
With Chelsea's fans again singing songs in support of Di Matteo, West Ham completed a miserable day for Benitez when another substitute Modibo Maiga struck in stoppage time. Chelsea remain in third place on 26 points with West Ham moving up to seventh on 22. Premier League leaders Manchester United (33 points) are in action at Reading in the day's late match after second-placed Manchester City (32) take on Everton at the Etihad Stadium. (Reporting by Martyn Herman, editing by Ed Osmond)