Archer becomes one of nine NRC councillors and along with sitting councillor Jack Craw becomes one of two elected representatives from the Whangārei urban constituency - NRC's second-largest by population.
The $80,000 byelection was called after the seat was left vacant by the resignation of former NRC councillor John Bain late last year over the council's vote for Māori constituencies.
NRC in October voted 7:1 in favour of Māori consistencies. Archer is against dedicated Māori seats.
Whangārei urban byelection voting began on January 26 and continued through Covid-19 level two restrictions.
All resident electors and non-resident ratepayer electors in the Whangārei urban constituency whose names were on the latest electoral roll were eligible to vote.
Archer's first full council meeting will be on Tuesday next week.