The Australian television star, who presents the current affairs show alongside Chris Bath, decided to step down as the anchorman of the series in order to return to his roots as a reporter.
The show's executive producer Mark Llewellyn told The Daily Telegraph: "[Mike was] keen to concentrate on reporting not hosting.
"This has been a big decision for Mike and I respect the fact it's tough being tethered to a studio once a week when you're working on stories too. Now he's free to do what he does so very well, to tell the best stories possible on Sunday Night!"
Munro added: "Anyone who knows me professionally also knows that I have always preferred being on the road in Australia reporting rather than being tied to a studio.
"When Sunday Night invited me on board as co-host, the contract said it was for just one year. I've done more than twice that and feel it's time to be a full-time reporter once again.''
Both Munro and Bath have previously denied rumors of a personality clash.
> Read our latest Australian TV news