Today Show host Karl Stefanovic has roasted his co-host, Ally Langdon, live on air after confirmation she is about to quit Nine’s morning show.

The network has confirmed Langdon will replace outgoing A Current Affair host Tracy Grimshaw.

Stefanovic opened Monday’s Today show by singing along to The Beach Boys song Kokomo: ‘She’ll go out to sea, when she goes to ACA!’

“Alison Langdon, everyone – the new host of A Current Affair, of course. Congratulations, Ally,” he finished with.

A blushing Langdon said she “wasn’t sure what you would do this morning. I knew it would be something”.

“I’m excited but bittersweet to be leaving the morning team, which is amazing,” she said.

Stefanovic finished with a warning, telling Langdon there’s “a big week planned for you … don’t go anywhere, not as if you can anyway”.

Nine’s confirmation of Langdon’s new gig on Sunday ended weeks of speculation that she was about to take over the ACA host’s chair from long-time host Grimshaw.

Langdon’s appointment came as she and Grimshaw laughed off rumours of an apparent feud – after footage emerged last week showing Grimshaw appearing to snub her replacement as she left the studio after her final ACA show last week.

Langdon laughed off the apparent rejection on Monday, laughingly saying the moment made her “heart break”.

Grimshaw was more serious.

“It’s come to my attention that some people are seriously suggesting I snubbed Ally here,” she tweeted last week.

“Of course I didn’t and wouldn’t. I was emotional, flustered and completely overwhelmed and just didn’t see her.”

Langdon’s move to prime time TV will mean the 43-year-old mother of two young children has more family-friendly work hours – and can avoid the 3am alarm that has been a feature of her time on morning TV.

Langdon’s husband is Michael Willesee, Jr., the son of former ACA host Mike Willesee.

“It’s a pretty special thing to the family if I’m honest,” a tearful Langdon said on Monday.

“A special thing for Mike, which has sort of surprised me how much emotion he’s had around it.”

“There’s the thought of how nice it would be had he been here.”

Langdon has been the Today co-host for three years and previously worked on 60 Minutes and for the Seven Network.

“It is such an incredible honour to be joining the A Current Affair team. A show I love, respect and have been watching since I was in school and Jana Wendt was host,” she said.

“I won’t lie – it’s daunting to be stepping into the role that Tracy has so brilliantly navigated for the past 17 years, with such warmth and compassion. I hope to bring my own warmth and compassion to the show as we continue to tell great stories that matter to our amazing viewers.

“I get it’s a big change for our audience and also for me personally.”

In another Nine announcement, Langdon’s replacement on Today will be reporter Sarah Abo. She will move from 60 Minutes, where she has been a reporter for three years.

Abo previously worked for SBS.

“I am thrilled to be joining the wonderful and hard-working team at Today, who manage to inform the nation every morning while also having a lot of fun,” she said.

“The 3am alarm will be an adjustment, but I’m looking forward to keeping Karl on his toes. I know Ally will make a success of the move to ACA and I can’t wait to watch her in the chair.”