Shanghai (26 million) and Mexico City and Sao Paulo, with populations of around 22 million each, follow close behind.
It is projected that 68 percent of the world's population will live in urban environments by 2050, compared to 55 percent in 2018. The report by the UN's population division goes on to say that while the global rural population will steadily increase and reach its apogee in a few years, the trend will decline by 2050.
Smaller towns with populations under 1 million (Tier 2 and 3 cities in India) people will see the biggest population explosions, according to this year's study.
The report also estimates that by 2030, the world could have 43 so-called megacities (up from 31 today, according to reports) - those with more than 10 million inhabitants - majority in developing countries.
This kind of population shift is typical of rapidly diversifying economies and a young population as people from villages move to cities like New Delhi and other urban centres around the country in search of employment opportunities.
The News Agency of Nigeria (NAN) reports that DESA in earlier report said: "By 2050, the third most populous country will be Nigeria, which now ranks seventh, and which is poised to replace the United States". Of this, India has the largest, at 893 million people, followed by China's 578 million. By 2020, Tokyo's population is projected to begin to decline, while Delhi is projected to continue growing and to become the most populous city in the world around 2028. However, some of the fastest-growing urban agglomerations are cities with fewer than a million inhabitants, many of them located in Asia and Africa.
Population Division director John Wilmoth said: "When urban growth is rapid, insuring access to housing, water, sanitation, electricity, public transport, education and health care for all is especially challenging". DESA stresses that sustainable urbanisation is essential to successful development.
The report recommends governments adopt better integrated policies on infrastructure and social services to improve the lives of urban and rural dwellers.