The Samoan powerhouse can play centre or wing and will join Wasps after the Super Rugby season, where he has been a standout performer for the Hurricanes already this year at centre and on the wing.
Leiua becomes the sixth high-profile signing for next season, after the announcements that Bradley Davies, James Gaskell, Rob Miller, Lorenzo Cittadini and Ruaridh Jackson will be joining the men in black and gold.