The "Jimmy Kimmel Live!" host took to Instagram Monday to share the update, saying he and his family "went into this experience with a lot of optimism and nearly as much fear and came out with a new valve inside a happy, healthy kid."
Kimmel has detailed his son's health struggles since Billy was born in 2017. Shortly after Billy's birth, Kimmel returned to his show and revealed that his son had been born with a rare congenital heart defect, and has given updates ever since.
He's also given high praise to the doctors and staff at Children's Hospital Los Angeles who have cared for Billy.
"Walking around this hospital, meeting parents at their most vulnerable, children in pain and the miracle workers who do everything in their considerable power to save them is a humbling experience."
ABC News contributed to this report.