Ben Haim, 31, has linked up with former Rs centre-back Ryan Nelsen who is now in charge of the MLS outfit.
The Israel international was boss Harry Redknapp's first signing in the January transfer window and made six appearances in all competitions this season.
He started Saturday's 1-0 defeat against Arsenal but will now move to Canada and Toronto, who are currently second from bottom in the Eastern Conference, until June 30 when his Loftus Road contract expires.
"Tal Ben Haim has been one of the top defenders in the EPL for nearly a decade. He captains his national team and Ryan thinks the world of him," said Toronto FC president and general manager Kevin Payne. "He's exactly the sort of defender we need."
The versatile defender, 31, has made over 300 appearances during nine seasons in England, eight of which have been in the Premier League, and has been capped 71 times for his country. His most recent cap came in the World Cup qualification win over Northern Ireland in March.
QPR midfielder Hogan Ephraim is already on loan with the Major League Soccer franchise, while Republic of Ireland international Darren O'Dea, Robert Earnshaw of Wales and Scotland's Steven Caldwell are also on the club's books.