Mike Hosking and Toni Street are leaving TVNZ's Seven Sharp.

The co-hosts announced their decision tonight on the second-to-last episode of the year.

Tomorrow night will be their last show.

At the end of tonight's episode, Hosking casually announced that they had good news, saying "we're off, we're done, we're finishing. Tomorrow night it is over".

He went on to say that the pair had come to the show four years ago and the pair had been challenged to fix the show after a troubled start.

"Four years later, Toni said to me 'I think I need to move on, my kids are starting school'... She's got radio and I've got radio and these are long hours and hard days. And so we thought, what better thing can you possibly do than call it a day and go out on a high."

Hosking went on to say when Toni decided to leave, he decided to leave as well.

Hosking will continue to host Newstalk ZB's breakfast show, while Street will continue on The Hits breakfast radio with Sarah Gandy and Sam Wallace.

Mike Hosking and Toni Street have been hosting Seven Sharp together for four years. (Photo / Norrie Montgomery)

Street told viewers she was cutting back on weeknight work to spend more time with family.

"Seven Sharp has been my dream job, I've absolutely loved my four years with Mike on the show," she said.

"It's been a privilege to be part of such a professional, fun and supportive team. I'm really proud of our ratings success and grateful to have been welcomed into the homes of so many New Zealanders."

Hosking said it was "always good to leave on your own terms and at your own time, often a rare trick in media".

John Gillespie, TVNZ's Head of News and Current Affairs, said the pair were "a dynamic team": "Their leadership at 7pm has been a defining force in our media landscape."

Street, who was named TV Personality of the Year at the 2017 NZ TV Awards, will be taking up new presenting opportunities with TVNZ in the year ahead.

"I'm really excited to be hosting the Commonwealth Games and the New Zealander of the Year Awards for TVNZ in 2018 and I look forward to working on other projects with my TVNZ family including within news and current affairs," she said.

Mike Hosking said it was "particularly important to me personally, to honour what has been one of the best combinations on television".

"Given we started together we end together. It is also always good to leave on your own terms and at your own time, often a rare trick in media."

An announcement on the show's new presenters is expected in January.