Jackie O breaks down on air while revealing her boss' four-year-old son has died.

Radio host Jackie O Henderson broke down in tears on her breakfast radio show on Monday while revealing heartbreaking news.

The 43-year-old told listeners that Tate, the four-year-old son of her KIIS FM boss content director Derek ‘DB’ Bargwanna, had recently passed away.

She first apologised to listeners if the team had seemed “flat” on air in the last week.

“[DB’s] four-year-old son Tate died in his sleep and it was completely unexpected and we don’t know why,” she said.

“He died peacefully in his sleep. And it has hit us all really hard and we’ve tried every day to go on air and carry on because DB would never want us to take a day off.”

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Jackie O. Image: Supplied.

She said the news had been traumatic for the whole KIIS "family" and many staff members attended Tate's funeral on the weekend.

She explained that the KIIS FM team regularly met people who had been through similar tragedies.

"At the time, when you meet these families, you have enormous empathy for what they're going through," she said.

"But it's not until it happens to someone you know and love dearly that you realise just how difficult that grief is and how it changes a family."

She sent love to DB, his wife Belinda and their two other children and concluded that she hopes they can begin the "healing process" following this tragedy.