This body can't take much more, striker says
The legendary striker, currently with Corinthians, has cited injury and fitness concerns as the reason for his bowing out months before his final contract was due to expire.
"My body aches. In my head I want to continue, but this body can't take much more," Ronaldo told Fantastico online magazine. "In recent days I have cried like a baby."
The forward has spent the last two years at Corinthians after a glorious spell in Europe with PSV Eindhoven, Barcelona, Inter, Real Madrid and AC Milan.
His one season at the Nou Camp is frequently cited as one of the greatest individual campaigns in footballing history, while his spells at San Siro and the Bernabeu were no less eventful.
Ronaldo is also widely regarded as one of Brazil's greatest ever players. He is the World Cup's all-time leading goalscorer, with 15 goals in four tournament appearances - two of which the South Americans would win.
Nonetheless, with Corinthians being eliminated from the Copa Libertadores early, and his physical condition preventing a consistent run in the Timao line-up, Ronaldo has now called it a day.
He will formally end his career at a press conference at Corinthians headquarters at 12:40pm local time (15:40 CET, 14:40 BST, 09:40 EST.)