Luke O'Nien penned a tribute on Twitter to the Chairboys after completing his transfer to Sunderland.
He wrote: "My time has come for me to move on from WWFC after one hell of a three year journey!
"I would like to thank every person connected to the club that has made my time so special. You have all helped me to develop both as a player and a person and I can't express my gratitude enough.
"I'm so proud to have played for such a great club, with so many great people who supported me every step of the way. You gave me my first opportunity in the Football League and to finish with a promotion with such an incredible bunch of boys was beyond special and it will stay with me forever!
"Receiving all the messages of love and support on Twitter has been overwhelming and has filled me with great joy. I have so much respect for everyone affiliated with Wycombe Wanderers and will remain a fan of the club forever!
"I wish you all the best for the upcoming season and will see you all soon."