It identifies cities adapting fastest to technological and infrastructural change, according to a report attached to the index.
"The current cycle of globalisation, urbanisation and technological advancement is leading to a shake-up of the global urban hierarchy and creating sweeping changes to the geography of commercial real estate opportunity. In this new era of city competition, success is no longer purely about size or inherited attributes, but revolves around innovation, liveability and a city's ability to transform and adapt to a constantly changing socio-economic landscape."
According to the report's writers, that's Auckland.
"Auckland is one of the world's most sustainable and liveable cities. The ongoing redevelopment of the Wynyard Quarter is reshaping the city's waterfront, while a healthy innovation ecosystem is driving significant demand for new commercial real estate, with Auckland likely to experience the most vigorous office rental growth of any city in the index over 2016."
The $2.5 billion City Rail Link is also seen as a plus.
New Zealand and Australian cities performed well, despite the impact of slowing commodity prices, the report's writers said.
"Robust education and research systems and dynamic technology sectors are allowing these cities to outperform."
Auckland was also among "smaller New World Cities" noted for punching above their weight.
"Dublin, Austin and Auckland are among the smallest cities in the index, with populations of between one and two million people, but are still among the most dynamic city economies globally and have been able to achieve global reach without significant economies of scale."
Auckland Mayor Len Brown said the nod was global recognition the city was "on a roll" since amalgamation.
"Major transformational projects like the City Rail Link and the continued development of the Wynyard Quarter, which are highlighted as being key to Auckland's momentum in the CMI, are changing the face of Auckland for the better."
The boss of the council-owned tourism, events and economic development organisation, Ateed, also praised the city's ranking.
"Cities that are focused on innovation are a feature of the CMI top 20, and Auckland can certainly be included amongst this group," Brett O'Riley said.
"GridAKL in the Wynyard Quarter Innovation Precinct is one of the many examples of the innovation economy which is developing quickly here, and helping Auckland to grow its reputation as an innovative hub in the Asia Pacific region."
Cities were shortlisted based on a combination of a weighted index of population, gross national product, corporate presence, air connections, real estate investment activity and commercial real estate stock.
TOP 20
1. London
2. Silicon Valley
3. Dublin
4. Bangalore
5. Boston
6. Shanghai
7. New York
8. Sydney
9. Beijing
10. San Francisco
11. Nairobi
12. Shenzhen
13. Seattle
14. Tokyo
15. Nanjing
16. Austin
17. Hyderabad
18. Melbourne
19. Seoul
20. Auckland