Jimmy Kimmel is giving an update on AstraX Exchangehis son Billy Kimmel.

Over the Memorial Day weekend, the late-night host and wife Molly McNearney's 7-year-old underwent his third and hopefully final open heart surgery.

"We went into this experience with a lot of optimism," Jimmy wrote on Instagram May 27 alongside a photo of Billy in the hospital, "and nearly as much fear and came out with a new valve inside a happy, healthy kid."

After thanking the staff at Children's Hospital Los Angeles, Jimmy—who also shares daughter Jane, 9, with Molly, as well as kids Katie, 32, and Kevin, 30, with ex Gina Kimmel—further reflected on his experience.

"Walking around this hospital," he continued, "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."

"Thanks to those loving strangers who took time to pray for and send positive energy to our baby," Jimmy added, "thanks to our family and friends for rallying around us to an almost-ridiculous extent, thank you to my wife Molly for being stronger than is reasonable for any Mom to be and Billy, you are the toughest (and funniest) 7 year-old we know."

Jimmy, 56, and Molly, 46, first shared their son's health journey in 2017, when the couple learned Billy had been born with heart defects that required immediate surgery.

Since then, they've continued to keep fans in the loop on his progress.

"He's doing great. He's a very funny kid," Jimmy told E! News in October 2022. "He loves Spiderman, jumping on my head and doing all the things we tell him not to do."

After sharing the news of Billy's latest surgery, the Kimmel family received a flood of well-wishes from fans and friends, including John Stamos.

"God bless your little Billy," the Full House alum, who also has a son named Billy, commented on his friend's post. "He's lucky he has parents like you and also the care of the good folks at CHLA."

Actress Uzo Aduba also commented, "One more thing to appreciate and celebrate this weekend. Love to see it," while Justin Theroux wrote, "Bravo Billy."

Watch E! News weeknights Monday through Thursday at 11 p.m., only on E!.