The powerful midfielder made almost 50 appearances for Rennes, scoring two goals, and attracted a host of European clubs
The 22-year-old midfielder is the club's third senior signing of the summer, moving from Rennes with a view to a permanent deal.
He completed a medical over the weekend and has now trained with the squad for the first time.
"I am really looking forward to playing for the fans and the manager," he told the club's official website.
"I want to help the team as much as I can as we aim for promotion. There were other clubs interested [but] I had a good feeling about Wolves as soon as I spoke to the manager.
"He told me personally about his plans and showed that interest in me which was good to hear."
At 6ft 3in, Doumbia has the reputation of being a strong midfielder and has insisted that he has the qualities needed to adapt to the npower Championship and help the club back to the top-flight.
He added: "I like to get from box to box but I also like to move forward with the ball and try and score goals. I am also a strong player and like to battle as well and will give everything I have for the Wolves shirt and for the club.
"It's up to the manager but I think I am ready to play tomorrow night even if it's just a short time."
Manager Stale Solbakken has expressed his delight at the capture, and says that he could be involved in the club's upcoming fixture against Shrewsbury.
"I am delighted we have managed to sign Tongo who will bring some more quality to the squad," he said.
"He also has good experience for a young player and made 26 appearances last season for a top six club in France.
"He is a box-to-box player who can operate in that central role defensively and offensively, and as well as being physically strong he is also good in possession.
"We'll have another look at him tomorrow but there is a chance he will be involved in the game against Shrewsbury."