Wentzel, a former South Africa Test player, left Leeds last week following their relegation from the Aviva Premiership, and the experienced lock becomes Wasps' 10th new signing for next season.
He was previously with Leicester before moving to Leeds, spending two seasons at each club.
Wentzel said: "It was a hard decision for me to leave Leeds, but I believe it is the best decision for me and the future of the club.
"I really enjoyed my time there and made some great friends. I must thank all my team-mates and the fans for their amazing support the past two years.
"On the other hand, I am really looking forward to join a club with a proud history like Wasps and believe I can play a part to get them back where they belong at the top of English and European rugby."
Wasps chief executive Chris Thomas added: "Marco will be a fantastic addition to our pack for next season.
"He has much-admired leadership qualities and we know that he is considered a fantastic professional in how he carries himself on and off the pitch."
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.