Jimmy Kimmel fought back tears as he revealed that his newborn son had to undergo emergency open-heart surgery shortly after his birth.

The US chat show host became emotional as he shared the news in the opening monologue on his show Jimmy Kimmel Live on Monday (May 1).

The TV star and host of this year's Oscars ceremony started by telling the audience that he had "a scary story" to tell but promised that it had "a happy ending".

Kimmel and his wife Molly McNearny welcomed son Billy on April 21, but just hours after his birth, their newborn baby began turning purple.

It was later discovered that Billy had a heart problem and he had to have open heart surgery at just three days old.

Kimmel described his son's surgery as "the longest three hours of my life".

The surgery was a success, and Billy was able to return home six days later. Kimmel said he was "doing great", while showing photos of him with his wife, their daughter Jane, two, and a smiling Billy.

The popular chat show host went on to deliver an impassioned speech about how every American family should be able to receive life-saving healthcare.

"No parent should ever have to decide if they can afford to save their child’s life," he told viewers while struggling to hold back tears.

Jimmy Kimmel and wife Molly's newborn son had to have emergency surgery

He went on to criticise US President Donald Trump's proposed cuts to the National Institutes of Health and praised Congress for instead calling for increased funding.

Kimmel said: "If your baby is going to die and it doesn't have to, it shouldn't matter how much money you make ... Whether you're a Republican or a Democrat or something else, we all agree on that, right?"

Partisan squabbles should not divide Americans on something "every decent person wants. We need to take care of each other", he added.

Following the broadcast, Kimmel thanked his fans for their support on Twitter.