Payet has signed a four-year contract at Lille and is looking forward to playing in the Champions League.
“It’s a huge satisfaction to finally be here in Lille,” he told the club’s official website.
“This was primarily a sporting decision. I was attracted by the future project of the club, a competitive team – here, there is everything to succeed.
“With LOSC I get to play in the Champions League and play a leading role in Ligue 1.
“Although so much happened in my four years at St Etienne, I needed a new adventure. I think Lille are the club that will help me with that.”
Payet will replace Gervinho, who is expected to join Arsenal in the summer.