The left-footed 18-year-old has been on the fringes of Carlo Ancelotti's first team this season, making eight mostly brief appearances.
A product of the Paris St Germain youth system, Rabiot is a France Under-19 international and comes in for Toulouse after the departure of Moussa Sissoko to Newcastle.
News of the deal, confirmed by both clubs on their official websites, emerged as PSG prepared to welcome David Beckham to their ranks, with the former England captain expected to sign today providing he passes a medical.
Toulouse announced: "Toulouse Football Club have just registered the loan of Adrien Rabiot until the end of the season."
Rabiot could face PSG in Toulouse colours tomorrow, when the teams play in Ligue 1.