The 27-year-old French-born Congolese international joins Walter Zenga's side after three seasons with Reims, who were relegated to France's Ligue 2 at the end of the last campaign, for a reported fee of around £2m.
"I'm very happy to be here with Wolves," Oniangue told the club's website. "I just want to say thank you for everybody who worked on me coming here.
"I like the vision of the club. Everybody wants to go to the Premier League - I like this challenge. It was my dream to come to England and today my dream is true! I just want to start training with my partners, win the matches and give joy to [the fans]."
Oniangue, who had 13 goals in 82 appearances for Reims, is Wolves' fifth new signing since their takeover by Chinese conglomerate Fosun International last month. The Championship outfit have also brought in Joao Teixeira, Jon Dadi Bodvarsson, Helder Costa and Silvio.