Scottish-born Steven MacDonald and his French wife Violaine became New Zealand citizens last week.
Mr MacDonald said he hoped that their two New Zealand-born children would now stop "rubbing it in" that they were Kiwis from birth.
"Now we're all on the same page," he said.
The couple were among 22 people from around the world who swore the oath or took the affirmation of allegiance at a ceremony led by Mayor John Carter at Te Ahu in Kaitaia.
Mr MacDonald said he had been recruited by the police in 2007, spending most of his time since then working as a detective in Kaitaia.
Not unusually, several of those who became citizens had not rushed into the decision. Briton Susan Bell said she had been in New Zealand for 40 years, and now felt like a "proper Kiwi".
"Thank you very much for having me in New Zealand," she said.
Her husband Alec said he had arrived in this country with his parents and siblings in 1952, aged four.
"Finally I have become a citizen, and it's great," he said.
Craig Forsyth had planned to leave New Zealand to work in Australia, but British friends here had persuaded him to stay. Then they set him up in a blind date.
"I've been struggling with the heat ever since," he said.
Nigela Holmes left Wales in 1965 to teach in New Zealand for one year and never went back, while Jithin Jacob, a registered nurse at Switzer Residential Care in Kaitaia, said he had been in New Zealand for five years. He and his wife were now expecting a Kiwi daughter.
The full list of candidates was:
Edgar Allen Baatjies (South African, now living in Kerikeri).
Alec and Susan Claire Bell (British, Kerikeri).
Paulus Stephanus and Lorraine Sandra Blignaut (South African, Russell).
Adriaan, Amanda and Jeroen Blok (Dutch, Kaitaia).
Timothy Charles Cooper (American, Taipa).
Craig Forsyth (Scottish, Kerikeri).
Nigela Jane Holmes (British/Canadian, Kerikeri).
Jithin Jacob (Indian, Kaitaia).
Ramandeep Kaur (Indian, Kerikeri).
Irina Lyubina (Russian, Ōruaiti).
Violaine Sophie Leonne (French) and Steven John MacDonald (Scottish, Cooper's Beach).
Filomena Ricciardi (Italian/American, Ōkaihau).
Shyam Sasidharan Sreedevi (Indian, Kaikohe).
Prudence Carol Marion and Cassidy Savannah Schuller (South African, Kerikeri).
Shayne Mary Storey (American, Ahipara).
Richard Marantal Talisayon (Filipino, Whangārei).