The lethal combination of Aaron Mclean and Craig Mackail-Smith took their combined tally for the season to 28 - 14 apiece - as Dale were undone.
Posh could well have been behind by the time Mclean slammed home with a rasping low 18th-minute drive from the edge of the box.
The home side doubled their advantage eight minutes into the second period when Mackail-Smith finished smartly through the legs of debutant Dale keeper Luke Daniels, who has been signed on an emergency loan from West Brom to solve a keeping crisis.
Visiting boss Keith Hill responded with an attacking double substitution that saw Anthony Elding and Jean-Louis Akpa Akpro introduced - and the latter gave the visitors a lifeline with 11 minutes remaining.
It came in controversial fashion, though, after he appeared to take down a long pass with his arm, but there was no disputing the quality of a volleyed finish past keeper Joe Lewis. However, Peterborough held on for the points.