The newly-demoted Championship side have been in the hunt for new players following the sales of Matt Jarvis and Steven Fletcher, which is believed to have accumulated a £24m transfer fund for the West Midlands outfit.
Boukari recently emerged as a replacement for winger Jarvis and the 25-year-old has put pen to paper on a four-year contract after completing a medical and agreeing personal terms over the weekend.
"I am so very happy to sign for Wolves," Boukari told the club's official website. "It will be a pleasure for me to play for the club and for the fans. I know the club have good supporters and I have been to the stadium which I think is beautiful.
"I know it is not the Premier League but that is not a problem because I just want to play football and hopefully I can do that at Wolves. I want to contribute and score goals and help the team do well and we want to aim for promotion."
Solbakken added: "I am delighted to have signed Razak. He is a winger with good speed who can play on both sides and give us more options in the wide areas.
"We have been aware of him and know he has played a lot of games for Rennes and had some good seasons."
Boukari will wear the number 17 shirt for the season.