Ramsey made his debut for Cardiff in 2006 before joining teams including Arsenal, Juventus and Nice. He returned to Cardiff for a second stint from 2023 to 2025.
His final appearance was for Mexican side Pumas UNAM, who terminated his contract last year.
"This has not been an easy decision to make," Ramsey said in a statement. "After a lot of consideration, I have decided to retire from football."
Ramsey won 86 caps for Wales after making his international debut in 2008, scoring 21 goals.
"It has been my privilege to wear the Welsh shirt and experience so many incredible moments in it. It would not have been possible without the incredible input of all the managers I have played under and all the staff who have helped me in many ways," he said.