The 32-year-old has signed a contract for "a couple of months" after impressing during a trial spell at Sandy Park.
Phibbs made 11 appearances for Exeter back in 2011-12 before moving to London Irish and then Leicester Tigers.
"We're going to sign him on a short-term deal," coach Rob Baxter told the club's official website. "He'll be here for a couple of months and then we'll re-assess the situation.
"He's a good player, he's someone we like and we've seen him before so we're quite comfortable to get him down here."
Exeter are currently in fourth place in the Aviva Premiership table following two wins and a defeat from their opening three matches.