After two years in Scotland, where he won six trophies with Brendan Rodgers’ side, the Frenchman has moved back to his homeland, with OL having brokered a late €22 million (£20m/26m) deal with the Europa League hopefuls.
Dembele, though, has said he needed to battle with his previous employers to ensure his dream move went through before the close of the window, with the 22-year-old having apparently criticised his previous employers via social media.
“It was a certainty that I wanted to come to Lyon,” he said. “I was determined to come here and the Celtic board had to back down. It was hard. I gave everything and, finally, it paid off.”
Lyon president Jean-Michel Aulas, meanwhile, was impressed with the desire the France Under-21 striker had to move to the club.
“I want to thank him because he’s talented and he’s shown determination to come here,” he said. “Without that, it would not have happened.
“Lyon has financial power that’s known all over Europe. Sometimes you have to use it. We had to be flexible and smart to finish negotiating and to reach an agreement with Celtic. I’m personally very happy, I’m satisfied and confident.”
Head coach Bruno Genesio, meanwhile, is looking forward to unleashing his new attacking weapon, who has arrived to replace Mariano Diaz, Cristiano Ronaldo’s replacement as Real Madrid's No.7.
“He’s the type of player we don’t have in our team,” he said. “He’s a real No.9. We’ll need him, especially in the Champions League. He gives me more possibilities. He can play alone or with another forward by his side.
“His desire to come to the club really impressed me. He wanted to join our project after our first discussions with him.”
Lyon, meanwhile, suffered a disappointing 1-0 loss to Nice on Friday.