The 25-year-old Ghanaian right-back joined Fiorentina from Brighton last summer for £5million on a three-year deal with ambitions to rebuild his career in Serie A.
Instead, he tore his anterior cruciate ligament just 21 minutes into only his second appearance — a start against Como in September — and did not play again. After 45 games missed and months of rehabilitation, both parties agreed a mutual termination was the cleanest resolution.
Lamptey posted his farewell on Instagram.
"I was really excited to play at the Franchi, to wear this shirt, to help the team on the pitch and give the fans something to cheer about. This was my goal, but I did not have the opportunity to achieve it. I am grateful for this experience and for getting to know all the people who supported me during my time in Florence."
He thanked every part of the club's structure in turn.
"I want to thank ACF Fiorentina, the President, all the directors, my teammates, the coaches, the technical staff and all the people who work behind the scenes."
He closed with a personal message to the supporters.
"I would also like to thank the fans for their support, even in the most difficult moments. I really appreciate it very much. I will always remember Fiorentina with great respect and I wish the club all the best. Forza Viola."
Lamptey broke through at Chelsea under Frank Lampard in 2019 before joining Brighton for £3million. He represented England at youth level before switching his international allegiance to Ghana.
He will not feature in their World Cup squad this summer. Now a free agent, the right-back's ability to convince clubs his body has recovered enough to deliver consistent football will be the central question of any recruitment process.