The 22-year-old loosehead is the second prop to join the province from the University of Cape Town - Stephen Knoop has made over 40 appearances for Connacht since transferring north at the start of the 2004/05 season.
Born in Grahamstown, Wilkinson offers a considerable presence at 6ft and over 18 stone. He was under the tutelage of former Ulster coach Alan Solomons and player Robbie Kempson at UCT.
Next season will be his first in the professional ranks.
Wilkinson said: "Under Alan Solomons and Robbie Kempson, UCT didn't lose a game and we ended up top of the Western Cape Super A League in 2005.
"I made my debut for them in 2004.
"Just before I came over (to Ireland) I was offered the chance to join the Western Province Currie Cup team, but I chose to come to Connacht instead.
"This is my first year as a pro and I'm really looking forward to the season ahead with Connacht."