Heather du Plessis-Allan will begin hosting TV3's new current affairs show, Story, in six weeks' time, alongside Duncan Garner.
But the former Seven Sharp reporter will remain in the political gallery reporting for TVNZ for the next four weeks.
TVNZ confirmed du Plessis-Allan will see out her notice with the company and has not been "walked" as is common practice in the media industry when employees defect to competing organisations.
Read more:
• Five obstacles Story has to overcome
A TVNZ spokesperson said: "I can confirm that Heather will be working out her notice period at TVNZ and that we will shortly commence looking for a political journalist to join our Wellington-based press gallery team."