RNZ reports the New Zealand-born, Australian-raised winger already has played 86 Super rugby matches, mostly for the Queensland Reds between 2008-2013.
Ioane, who's played 35 tests, has since played for the Stade Francais in France and is about to return to his second season with the Honda Heat in Japan.
"I have had a great time playing in France and Japan, but the opportunity to be part of a New Zealand Super Rugby team is too good to pass up," said Ioane.
The recently appointed Crusaders Coach Scott Robertson said Ioane was a key signing for the team.
"Digby is a massive talent, who we believe still has plenty of top class playing years left in him despite his experience," he said.
"We also know he will make a huge contribution off the field, with his energy, great character and good humour."
Former Wallabies winger Digby Ioane on the burst against the All Blacks in 2011. Photo: Photosport