Auckland Central MP Nikki Kaye will return next year to defend her electorate seat in the general election.
The National MP, who is undergoing treatment for breast cancer, returned to Parliament briefly today for a National Party caucus discussion on a new party leader. Prime Minister John Key announced his resignation yesterday.
"It's good to be back," Ms Kaye said.
Ms Kaye, 36, paid tribute to Mr Key, saying he was supportive through a tough time.
"I don't want to cry, but he has been an incredible rock during this period," she said.
"To all of those people who get cancer, particularly breast cancer sufferers out there, I want to acknowledge the courage they have."
Key was "just been the most incredible person" and "a great friend".
"He's also just given me so much space to get well."
"While I'm gutted for him, personally, I'm delighted that Bronagh and Stephie and Max are going to have their dad back."
"Our party is very strong and we will continue to fight."
Ms Kaye was still receiving treatment, but intended to return to Parliament early next year to resume full duties and contest her Auckland Central seat.
She backs Bill English for the party leadership, as does Mr Key, Michael Woodhouse, Nathan Guy, Anne Tolley, Louise Upston and Hekia Parata.
Ms Kaye took a leave of absence from her ministerial roles in September after her breast cancer diagnosis.
She thanked the media for "giving me that space to recover".
Gerry Brownlee took over her Civil Defence portfolio. Nathan Guy was acting ACC Minister. Ms Tolley was acting as Minister for Youth and Ms Parata took over Ms Kaye's Associate Education responsibilities.
Ms Kaye has been the National MP for Auckland Central since 2008.