The new calculations take into account changes in production and consumption since the last time the exercise was carried out in 1990 and indicated that the economy grew to USD 453 billion in 2012, instead of USD 264 billion as measured by the World Bank for that year.
South Africa's economy was at USD 384 billion in 2012, according to the World Bank.
Estimates for 2013 indicated further expansion to USD 510 billion, Nigeria's chief statistician, Yemi Kale, told a news conference in the capital, Abuja.
"On a per capita basis, Nigeria is number 121 in the world. So, we have a total GDP size where we have moved up to 26th," the former World Bank managing director added.
The widely expected results are based on calculations taking into account a range of new sectors and industries that were negligible or non-existent in 1990.
They include the massive mobile telephones market, music and the hugely popular local film industry, Nollywood.
According to the International Monetary Fund, Nigeria averaged 6.8 per cent annual growth from 2005 to 2013 and was projected to grow this year at a rate of 7.4 per cent.
That compares to a little over five per cent between 2005 and 2008-9 in South Africa, which has struggled to go beyond 3.5 per cent since.
Global investors have been eyeing Nigeria as a potential boom market, along the lines of the BRIC countries (Brazil, Russia, India and China) 10 years ago.
Okonjo-Iweala said GDP per capita in Nigeria was now USD 2,688 -- up from USD 1,555 in 2012 -- taking the country from 135th position in the world to 121st.
GDP per capita in South Africa in comparison was USD 7,508.
