The England flanker was released by French club Stade Francais at the end of last season, but had said he was in no rush to resolve his future at club level as he focuses on preparations for the upcoming World Cup with Martin Johnson's squad.
But the 26-year-old is soon to rejoin the club where he started his career before departing for Paris in 2009, although he will firstly embark on a spell with the Ricoh Black Rams in Japan and aims to follow that up with a season of Super Rugby, before heading back to England next summer.
Haskell told the Wasps website: "I was very flattered and humbled by Wasps enthusiasm and commitment to re-sign me.
"As everyone knows my family and I were fans of Wasps long before I was privileged to be invited to join the Wasps Academy.
"So returning to the club that has been pivotal in propelling me to where I am fortunate enough to stand today was not one of the harder decisions I have ever had to make.
"I have had lengthy dialogue with the senior management at Wasps and am in no doubt as to their commitment and energy in endeavouring to restore the club to its rightful position at the top of the tree.
"I am hugely encouraged by the quality of the new and proposed signings the club has made.
"Wasps have been extremely far-sighted and generous in allowing me to continue my overseas adventures for one more season. I have a plan which seeks to maximise this unique opportunity before I return to Wasps by experiencing playing the game in a number of different arenas.
"I hope by exposing myself to different coaching, cultures and playing styles, I will gain a greater understanding of the world game, which will hopefully only be beneficial to both Wasps and myself for the 2012/13 season."
Haskell's decision to head to Japan and on to Super Rugby post World Cup will see his international career put on hold.
The Japanese Top League season will run until February, which is when the Super Rugby season will kick into gear, which means Haskell will be unavailable for England's Six Nations title defence, although he will be available for selection when Johnson picks his squad for next summer's tour of South Africa.
But the return to Wasps, who confirmed Dai Young as their new director of rugby earlier this month, will bring Haskell in line with the Rugby Football Union's stance, due to be enforced after the World Cup, that only home-based players be selected for the national side.
Wasps chief executive Chris Thomas added: "We will be delighted to welcome James back to Wasps next year.
"James is one of the real success stories from the club's academy, coming right through our age-grade structure to become one of the best back-row players in the world.
"James is a world-class player and everyone at the club is excited by his return."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.