The Frenchman said “all great things must come to an end” having signed a four-year deal with the Premier League side who are managed by France legend Patrick Viera.
A deal of £14million, which could rise to £18.5million, was completed on Tuesday night, bringing an end to Edouard’s four-year stay at Parkhead.
During his time at Celtic, he scored 77 goals and helped the club win three league titles, plus four domestic cups.
"All great things must come to an end,” he tweeted. “My time at Celtic has come to an end.
"I have wonderful memories at my time with the club. I can not thank the fans enough for the support and love throughout my 4 years with the club.
“I would like to thank the players, board and everyone connected to the club. I wish the club all the best for the future.”