Jooste, 31, won under-19 and under-21 honours for South Africa, and he moves to Welford Road from French club Bourgoin, where he spent seven seasons.
He joins the Tigers following the recent injury-enforced retirements of Ben Woods and Craig Newby.
"Wessel is a big man, a good ball-carrier and can play right across the back-row and in the second-row," Leicester rugby director Richard Cockerill said.
"He has played a lot of his rugby in France and has captained Bourgoin.
"We believe he will be a good signing for us and will complement the other guys we've got in the squad."
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.