The fund, commonly known as the Cullen fund after its founder, former finance minister Sir Michael Cullen, invests globally to help pre-fund New Zealanders' universal superannuation entitlements.
The fund is now worth $23 billion compared with $19 billion a year ago.
Guardians of New Zealand Superannuation chairman Gavin Walker said the annual return capped off a successful 12 months for the fund.
''While the fund's performance over the 2012-13 year has been exceptional, it should not be seen as a precursor of ongoing returns at the same level.''
Chief executive Adrian Orr said the strong performance was due to a heavy weighting towards growth assets, including global equities, and from valuation lifts in key domestic assets Kaingaroa and Z Energy.
The fund recently sold down part of its share in Z Energy, which it owned with Infratil. Z is now listed on the NZX.
Mr Orr said with the fund not scheduled to pay out money until 2030, it remained focused on long-term growth-oriented investment strategies and returns.
''We are prepared to weather the inevitable short-term volatility and will look to profit from it where we can.''
The fund's previous highest annual return was 25.1% in 2010-11. Since inception in September 2003, the fund had returned 8.8% a year and was ''comfortably ahead'' of its key long-term performance benchmarks, Mr Orr said.
Over the time frame, the fund had beaten the 90-day Treasury bill return by 3.9% a year, or $6 billion, and was ahead of its passive reference portfolio benchmark by 1.14% a year, or $2 billion.
The guardians expected over the long term the fund would beat the Treasury bill return by at least 2.5%, by 0.5% a year. For the 2012-12 year, the fund achieved its strongest annual results compared with its benchmarks, beating the reference portfolio by 7.36% and the bill return by 23.43%.
In New Zealand, the fund has stakes listed companies including Fletcher Building, Telecom, Auckland International Airport, SkyCity Entertainment, Contact Energy, Fisher and Paykel Healthcare, NZ Refining Company, Ryman Healthcare, Trade me and Sky Network Television.
Internationally, it has stakes in Transurban Group, Zurich Airport, Simon Property Group, Copenhagen Airport, Exxon Mobile, Samsung Electronics, Mitsubishi Estate, Apple and Westpac.
