Dewald Brevis will play for the St Kitts & Nevis Patriots in the first edition of the 6ixty tournament.
The Patriots have also picked up Proteas all-rounder Dwaine Pretorius. Brevis and Pretorius will also represent the franchise in the Caribbean Premier League, which starts on 31 August.
Other South Africans in the six-team 6ixty tournament are Migael Pretorius (Jamaica Tallawahs), Corbin Bosch (Barbados Royals) and Heinrich Klaasen (Guyana Amazon Warriors).
The new West Indian tournament will have a 10-over format with each innings having only six wickets.
Bowlers will bowl back-to-back five overs from each end instead of changing it after each over.