The 26-year-old loose forward, who has 40 caps and who played for England at Otago Stadium during the recent World Cup, is the first overseas international player to be signed by the Highlanders.
Haskell will join the franchise following a spell with his current club, the Ricoh Black Rams in Japan.
He will then move to Wasps at the end of the Super 15 season.
The squad, announced in Dunedin by coach Jamie Joseph, has eight new players - including Haskell, New Zealand internationals Hosea Gear and Andrew Hore, and former All Black Tamati Ellison - and four players who are new to Super Rugby.
Joseph believes Haskell brings international experience and versatility to the Highlanders mix.
"Those are compelling reasons to select him," he said. "He's a good footy player and also a bit of a character.
"He's played in France, he's in Japan, money wasn't an issue so he's coming down here to play rugby. He wants to come down and have a go.
"He gives us tremendous flexibility on our bench. He can play in all three loose forward positions. We have that ability now not to have to play guys week in and week out, as we had to do last season."
Haskell himself is looking forward to the challenge of Super rugby.
"I have always wanted to test myself in a new environment and in a new culture, both as player and as an individual," he told the Times.
"I think it will help me in my desire to improve and become a better player for England.
"The move to New Zealand and playing with some of the best players in the world in the country which holds the World Cup is another important step in that direction.
"That is the ultimate playing environment."
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