Quansah left Liverpool for Bayer yesterday in a £35m move.
Posting on Instagram last night, Quansah said: "From the moment I walked through the doors of the Academy at 5 years old, I dreamed of one day wearing the Liverpool shirt at Anfield. 17 years later, I can now say I have lived that dream.
"To my teammates, thank you for welcoming me, pushing me, and believing in me. I’ve learned so much from sharing the pitch and dressing room with such amazing people and will never forget the incredible memories we’ve had.
"To the staff, the coaches, and everyone behind the scenes, your belief and dedication have always been a constant source of motivation. You have helped me grow not only as a footballer, but as a person as well.
"And to the fans, your support has always been unmatched. Whether at Anfield or away from home, hearing you sing never failed to inspire me. I will carry that with me wherever I go.
"Liverpool will always hold a special place in my heart. It’s not just a club — it’s a family! This is goodbye for now, but I’ll always be watching — once a Red, always a Red."