The versatile 24-year-old forward has struggled with a knee injury this season, which has restricted him to just one appearance for the Cherries.
McQuoid, who played an influential role in the south-coast club's promotion campaign last season, will head to London Road to help with Posh's top-six ambitions.
The Northern Ireland international can play up-front, out wide or just off the striker will go straight into the squad to face Walsall on Friday night.
He will also be available for the club's Johnstone's Paint Trophy Area final second-leg against Swindon on Monday night.
- Sports & Recreation