The agreement substantially deepens the relationship between the two airlines which are both part of the 27-member Star Alliance.
For passengers codeshare arrangements make booking easier and travel more convenient with better co-ordination of flights, baggage checked through the entire journey. They can mean cheaper tickets from a hub airport to the final destination. There is no indication of changes to overall fares in today's announcement but cheaper promotional deals are often offered at the launch of big partnerships.
Travel through Singapore will be attractive as its Changi Airport has a reputation of being one the best in the world. The deal is subject to regulatory approval but flights could start as early as December this year.
While Air New Zealand will take over half of the flights currently operated by Singapore Airlines to this country, the Singaporean carrier will also upgrade its services, moving towards flying its A380 on a seasonal basis to this country for the first time.
Air New Zealand says the deal could boost capacity between New Zealand and Singapore by up to 30 per cent year round over time.
Air New Zealand last flew to Singapore in 2006 but struggled to make money on the route. The airline has been chasing partnerships with others rather than operating alone as a small carrier flying into big markets where rivals have a home ground advantage with marketing and sales distribution power and favourable treatment from airports.
Singapore Airlines has flown here since 1976, flying up to 19 round trips a week to Auckland and Christchurch but like many other overseas carriers flying here it has had difficulty making money at times.
Air New Zealand chief executive Christopher Luxon said his airline was on a positive growth trajectory with a focus on the Pacific Rim.
"An alliance with Singapore Airlines clearly fits our business objectives of working with the right partners in the right markets to deliver seamless customer journeys," he said.
Luxon, who took over as chief executive of Air New Zealand a year ago, sits on the Star Alliance board with Singapore's head Goh Choon Phong, who is also relatively new in the top job.
Goh said the alliance was another example of his airline's commitment to the southwest Pacific.
"This is a genuine win-win partnership enabling Singapore Airlines and Air New Zealand to work together to provide more flight frequency and enhanced travel options for our customers."
Air New Zealand last year started a revenue sharing deal with Cathay Pacific on the carriers' Auckland-Hong Kong route.
New routes
Codeshare and co-ordinated sales to:
• France
• Germany
• Italy
• India
• Indonesia
• Malaysia
• Netherlands
• Philippines
• South Africa
• Spain
• Switzerland
• Thailand
• Britain
• Vietnam
Codeshare only:
• Bangladesh
• Brunei
• Burma
• Cambodia
• East Timor
• Maldives
• Nepal
• Russia
• Saudi Arabia
• Sri Lanka
• Turkey
• United Arab Emirates
Singapore - NZ Flights
• New daily Air NZ Auckland-Singapore service replaces and expands Singapore Airlines' five times a week evening service using refitted Boeing 777-200 aircraft
• Singapore Airlines progressively introduces an A380 to its Auckland-Singapore daytime service
• Singapore retains its daily service to Christchurch using its refitted 777-200 aircraft.