The Raiders announced on Monday that Waqa will remain part of their squad until round 16 before being released to play in the Top 14.
The Fijian flyer has played for Canberra's feeder club Mounties in the first two rounds of this season, with Raiders coach Ricky Stuart preferring Edrick Lee and Jordan Rapana as his wingers.
Waqa joined the Raiders last season from Melbourne, where he played on the wing in their 2012 premiership-winning side.
He was linked to a move to French rugby even before he arrived in the nation's capital.
Waqa will link with two former Canberra residents at Grenoble, with former Brumbies forwards Ben Hand and Peter Kimlin currently with the club based at the foot of the French Alps in the country's south-east.
