The election will be held on September 20, Prime Minister John Key has announced this afternoon.
Key said he called the governor-general to inform him of the date yesterday.
"I'm announcing the election date well in advance as I believe this gives New Zealanders some certainty and is in the country's best interests," Key said.
"It is my practice to be up-front with the New Zealand public and provide plenty of notice about election timing."
The Government's intention was that the House should rise on July 31 for its last sitting before the election, with Parliament dissolving on August 14.
Holding the election in September would allow the Prime Minister to attend the G20 in Brisbane in November.
A number of world leaders had expressed an interest in visiting New Zealand around the time of the G20, however this would not be practical during an election campaign.
October was not suitable as it could take weeks to form a coalition, Key said.
Labour leader David Cunliffe welcomed the election date.
"We're ready, we're up for this, it's game on," Cunliffe said, dismissing concerns that September weather could hamper turnout.
The election would be about "creating opportunity for all New Zealanders, it's going to be about an economy that creates and shares value. It's going to be about a fairer and more inclusive society with opportunities for all, and it's about building a new passion for being New Zealanders, proud of our culture and our environment and our heritage".
His personal view was that elections should permanently move to a "September to September" cycle as international summits tended to be held in November. The time it took for coalition agreements to be struck meant the House could be required to sit in January, he said.
Key said there was little political advantage in holding onto the election date.
The Prime Minister's office informed the Government's support parties this afternoon but the Opposition did not get any warning about the announcement.
Key denied the possibility of higher interest rates was a factor in the decision. The Reserve Bank of New Zealand is expected to raise the official cash rate later this week, and possibly on several more occasions this year.
Key said increased interest rates showed confidence in the economy.
Elections are generally held in November although in 2002 the election was held in June and in 2005 it was held in September.
Green Party co-leader Russel Norman welcomed the advance notice but said the party preferred elections when the weather was better as that helped voter turnout.
New Zealand First leader Winston Peters said the party was ready for the "early" election.
"We believe the country will welcome the early election date because hope is finally within sight."
Punters on the Victoria University prediction website iPredict had favoured a September election in recent days, although September 27 was the most likely until early this afternoon.
Key said Writ Day, when the governor-general issues a formal direction to the Electoral Commission to hold the election, would be August 20.
The Electoral Commission said advance and overseas voting will open on September 3.
Official results would be on October 4, the commission said.
Key wanted to announce the election before his trip to China next week. National would campaign hard on its record rebuilding Christchurch, improving the economy and protecting the most vulnerable.
The campaign would also be on National's track record, new initiatives such as its education plan, and the fact that National was "very much in touch" with what Kiwis wanted.
He said New Zealand's progress in recent years had not happened by accident.
Key will make a speech about the future of the New Zealand flag tomorrow, but he declined to say whether a referendum would be held with the election, saying he didn't want the reporters to open all of their presents today.
- Fairfax Media
What do the stars have in store for you today?
Test your mind with our puzzles
The Little Things, Dilbert, Tom Scott and others