Economist Geoff Simmons will stand in the Mt Albert by-election for Gareth Morgan's Opportunities Party.
Mr Simmons, the party's chief of staff, will go up against Labour's Jacinda Ardern and the Green Party's Julie Anne Genter in the vote on 25 February.
Gareth Morgan founded The Opportunities Party three months ago. At the time he said the party would not form a coalition but could happily work with either Labour or National.
National has decided not to put up a candidate in Mt Albert - considered a strong Labour seat. It was formerly held by David Shearer who resigned as a Labour MP to take a United Nations job.
Mr Morgan said today he wanted to offer voters more choice given National has decided not to contest the seat.
Mr Simmons grew up around the Mount Albert electorate, but it is not currently his permanent home. He says he would move to the electorate if he won the by-election.
Nominations have closed and the final list of candidates is expected to be announced by the Electoral Commission later today.