Pettybourne, 25, will join on a two-year contract for seasons 2014 and 2015 and he is excited about the move.
He said, “I’m really looking forward to this new challenge with Wigan. I just feel the time is right now as I have always been interested in playing overseas and I feel I have plenty to offer.
“I have spoken to Shaun Wane and have been extremely impressed in what he has had to say. It’s very exciting and I am looking forward to joining Wigan but at the same time I will be focused on doing my very best for the Wests Tigers for the remainder of this season.”