Prime Minister John Key vowed that New Zealand would be a "small country with a loud voice" after it won a seat on the UN Security Council.
New Zealand secured 145 votes in the 193-nation General Assembly to win a non-permanent seats.
Four other countries won a seat: Spain, Angola, Malaysia and Venezuela.
The 15-member council has five permanent members - the US, UK, France, Russia and China - and 10 non-permanent seats, filled on a rotating basis.
The five seats allocated this year include one country each from Africa, Asia and Latin America and two from the "Western European and Others" grouping.
Mr Key said he was pleased a nation of just 4.5 million people with modest resources could win, amid concerns in recent years about wealthy nations pledging tens of millions of dollars in aid in return for support.
"We just can't write out cheques to get ourselves on the Security Council. We didn't throw a lot of money at it," Mr Key told reporters.
"We just put on display the credentials of New Zealand, which is a country that's seen as an honest broker, someone that stands up for what's right."
The conservative leader said New Zealand's success should encourage other small nations to run for a seat on the council.
Push for diplomacy
He said one factor that had helped New Zealand was memories of its last stint on the security council in 1993-4, when it argued in favour of early UN intervention to prevent the Rwanda genocide.
Mr Key said he was convinced that a diplomatic solution was needed to defeat Islamic State (IS) militants in Iraq and Syria, one of the crises at the top of the current world agenda.
"We don't accept the things that [IS] are doing or the particular form of Islam that they're preaching but nevertheless, diplomacy always has an important role to play if you ultimately want to find long-term solutions," he told reporters.
Turkey, which has the threat of IS on its doorstep, had also campaigned for a seat on the council but eventually lost out to Spain.
The BBC's Nick Bryant at the UN said it was a diplomatic setback for Turkey, which has faced criticism for not doing enough to stop the advance of IS just over its border with Syria in the town of Kobane.
Its campaign for a two-year temporary seat might also have been hindered by the fact that it last served on the Security Council only four years ago, our correspondent adds.
New Zealand, Spain, Angola, Malaysia and Venezuela will begin their two-year terms on the council in January.
They will join five other non-permanent members: Chad, Chile, Jordan, Lithuania and Nigeria.
Argentina, Australia, Luxembourg, Rwanda and South Korea will step down at the end of this year.