Trevor Hall has ended his contract with Biarritz and has signed a three-year deal with the Lions.
The former Lions lock, who is 31, left the franchise in 2006 when Loffie Eloff became coach to join the Top 14 side. His Biarritz contract still has a year to run, but he asked for an extension, which they denied.
He then asked for an early release, which they granted, and he signed with his former union.
Hall has also played blindside flank this season, playing 24 matches, of which he started 21.