South Africa lock Franco Mostert joined English Premiership club Gloucester on Wednesday.
Mostert, 27, has agreed to move to Kingsholm from 2017 Super Rugby finalists the Lions.
Capped 18 times by the Springboks, Mostert will be reunited with former Lions boss Johan Ackermann, who is now Gloucester's head coach.
Mostert, who has captained the Lions this year, was recently named in South Africa's squad for the forthcoming three-Test series against England.
Gloucester rugby director David Humphreys said: "Franco has proved to be one of the stars of Super Rugby.
"We know the Gloucester fans love their physical, hard-working forwards, and Franco is exactly that.
"He has so many quality attributes, and this is a big sign of our intent as a squad to push to the next level.
"Obviously, Franco is a player that Johan is very familiar with, and Franco will know what Johan expects from his players, and he is the type of character that will fit in well to our squad.
"He is a current international and has been captaining the Lions throughout the Super Rugby season, so he displays leadership skills that will again benefit our squad."
Lions star Franco Mostert has signed for Gloucester