Doucoure joined Everton from Watford in 2020 and played a key role in their successful battles to avoid relegation in recent years.
The 32-year-old hit the winner when Everton beat Bournemouth 1-0 at Goodison Park to stay up on the final day of the 2022-23 season.
Speaking in a video posted on social media, Doucoure said: "Everton means a lot for me. Obviously the past five years it's been hard but I will always remember my time as a dream for me.
"I'm sad to leave the club but I think the time has come for a new chapter for me and for the club as well. I will always be grateful for what the club did for me.
"My best memory, I will say it will be the goal I scored against Bournemouth to keep the club in the Premier League. It was a wonderful moment for me and for the club as well."
Doucoure, who is out of contract in June, was part of David Moyes' team on Sunday when they beat Southampton 2-0 in their final match at Goodison Park.
Everton are relocating to their new arena at Bramley-Moore Dock from next season.
© 2025 AFP