The 22-year-old played the full 90 minutes against the Tykes as a single goal from Steve Mounie gave Town the win at Oakwell.
The right-back began his career at Lens, beginning with the B side, before making 21 senior appearances between 2013-2015.
He stayed with the Stade Bollart-Delelis side on loan after joining Rennes in a £2.5m deal in January 2015, but he suffered a severe ligament injury which kept him out of action for over a year.
Since returning from injury, Cavare made just five appearances last season and only two of those were in the league. The former France U20 international, who is contracted at Rennes until the summer of 2018, was linked with a move to Blackburn Rovers and Reims in January.
Mounie on target again as Terriers claim victory at Barnsley
Huddersfield Town's record signing Steve Mounie scored his third goal in four games to give Town the win in a friendly with Yorkshire rivals Barnsley on Saturday.
The striker scored the only goal of the game in the last minute when he latched on to a long kick up field from goalkeeper Jonas Lossl to score with an impressive lob.
Town controlled for large parts and most of the first-team got 90 minutes under their belts, except for Philip Billing and Joe Lolley who were taken off as a precaution.
Mounie and fellow new signing Tom Ince had chances in the opening 30 minutes but it was Barnsley who had the best chance to go in front.
Former Town winger Adam Hammill was involved winning the free-kick that saw Alex Mowatt find Stefan Payne in the box but Lossl spread himself well to deny the home side taking the lead.
Joe Lolley impressed in the 'number 10' role
Huddersfield manager David Wagner spoke during the week of giving existing players a chance during pre-season and the display of Lolley may give him food for thought.
The 24-year-old played in the 'number 10' role behind the lone striker of Mounie and was unlucky not to get on the scoresheet. He fired just over at the end of the first half before jinxing his way past three players into the Barnsley penalty area only to see his shot blocked.
Chris Lowe then saw his effort smartly pushed away by Tykes stopper Adam Davies before Lolley was again involved forcing a defender into an error that allowed him to set up Collin Quaner, but again Davies was there to deny.
Davies again denied Qauner after being played in by Ince while Hammill curled an effort wide at the other end.
Sean Scannell had a looping header that hit the bar but it was Mounie that made the breakthrough late on when he outpaced Angus MacDonald to lob the ball over the onrushing Davies from Lossl's long kick up field.