Manchester: The Portuguese star also revealed the birth of a baby girl with partner Georgina Rodriguez, with the pair previously stating that they had been expecting twins.
He further asked for privacy at this very difficult time.
"It is with our deepest sadness we have to announce that our baby boy has passed away. It is the greatest pain that any parents can feel. Only the birth of our baby girl gives us the strength to live this moment with some hope and happiness. We would like to thank the doctors and nurses for all their expert care and support. We are all devastated at this loss and we kindly ask for privacy at this very difficult time. Our baby boy, you are our angel. We will always love you," Cristiano Ronaldo posted on his Instagram.
Ronaldo is a father to four other children, sons Cristiano Jr and Mateo, and daughters Eva and Alana.
In 2017, Georgina Rodriguez who is Ronaldo's current partner gave birth to a baby girl - her first with Ronaldo and the Portugal star's fourth child.
In 2021, the couple then announced that they were expecting twins.
The 37-year old Ronaldo, five-times world player of the year, rejoined Manchester United last year after winning multiple trophies with Real Madrid and Juventus.