Wasps get an All Black sting
This follows after he was left out of his country's squad for the World Cup.
Piutau will join Celtic League side Ulster next July, but they aren't able to include him in their squad for this current campaign as their foreign allocation is full.
And when the 23-year-old missed out on a place in the All Blacks' final 31-man squad for the World Cup, which gets underway next week, Piutau opted to play for Wasps in 2015-16.
"When the opportunity arose to play for Wasps I was excited," Piutau said.
"It's a club with a proud history and one that has recruited very well over the last few seasons.
"I know Alapati Leiua from New Zealand and am looking forward to playing with him, as well as continuing to play alongside Frank Halai who I have played a lot with.
"I have also heard great things about playing at the Ricoh Arena and the crowd support there and I look forward to making a contribution to what will hopefully be a very successful season."
Piutau, who can play at fullback, wing or centre, previously played for Auckland in New Zealand's NPC, the Blues in Super Rugby and has been capped 17 times for New Zealand – after making his international debut against France in June 2013.
Later that year he scored his first international points with two tries against Japan in Tokyo in November, before scoring again against the French in a 26-19 win in Paris a week later.
The last of his five All Blacks tries came in July during a 39-18 Rugby Championship win over Argentina in Christchurch.
Wasps' Director of Rugby Dai Young added: "The opportunity arose for us to sign Charles and we jumped at the chance.
"His addition will bolster the strong recruitment we've already made for the new season, complementing the talented squad we already have in place
"Charles will really add to what we are doing at Wasps. We have a number of players, including Charles, who can cover a number of positions in our backline.
"If we want to be successful, we need to have strength in depth, particularly this season when you switch between Premiership and European games week after week.
"You are going to pick up bumps and bruises, so it's really important to have players who can play in a couple of positions and strength in depth across the board. I believe Charles can add to that. If everyone is fit, it will provide real competition for selection and will give Wasps a real quality backline."
