The 25 Most Populous Cities in the World

The United Nations describes a megacity as an urban center that accommodates more than 10 million inhabitants.

The megacities in this list, also face "mega" challenges, including providing water services and managing their environment; however, urbanization does not mean a threat to the natural environment.

'Well-planned, compact urban development generates immense environmental value', according to the U.N.'s World Cities Report 2020

The cities listed below are the most populous in the world, according a 2018 U.N. report.

1. Tokyo, Japan

Population in Urban Area: 37,340,000

Population in City Area: 13.96 m

Tokyo, Mount.Fuji, Japan at night
Aerial view of Tokyo city with Tokyo tower and Mount.Fuji, Japan at night.Japan’s capital is the largest urban area in the world with a population of over 37 million people. Getty Images

Tokyo is the most populated city in the world and the largest "Megacity" in the world.

The city dubbed the "Capital of the East" is located on the eastern coast of the Japanese main island of Honshu.

2. Delhi, India

Population in Urban Area: 31,181,000

Population in City Area: 20,591,874

46 Delhi
The current metro area population of Delhi in 2021 is 31,181,000, a 2.94% increase from 2020. Getty Images

Delhi, also known as the National Capital Territory of India is the largest city in the country. According to a U.N. report, the Indian capital is expected to retain the spot of the world's second most populous city through at least 2030.

3. Shanghai, China

Population in Urban Area: 27,796,000

Population in City Area: 22,315,474

The metro area population of Shanghai in 2021 is 27,796,000, a 2.73% increase from 2020. Getty

This is China's most populated and also wealthiest city. Situated in the Yangtze River Delta, in eastern China, it has a huge business district, two large airports (Pudong and Hongqiao) and the world's fastest train (the Shanghai Maglev).

4. São Paulo, Brazil

Population in Urban Area: 22,043,028

Population in City Area: 10,021,295

07 Sao Paulo
The metro area population of Sao Paulo in 2021 is 22,237,000. Getty Images

This bustling metropolis in southeast Brazil, is the largest city of the Southern Hemisphere and the largest Portuguese-speaking city in the world.

5. Mexico City, Mexico

Population in Urban Area: 21,919,000

Population in City Area:12,294,193

Mexico City
The most populous city in North America, an estimated 12 million people live in Mexico city. Aerial view of low visibility due to air pollution in Mexico City on April 22, 2021 in Mexico City, Mexico. After registering high levels of ozone the environmental comission (CAMe) activated the "Hoy no circula" protocol which establishes groups of vehicles that are not allowed to drive between 5 am and 10 pm. Photo by Hector Vivas/Getty Images/Getty Images

Greater Mexico City refers to Mexico City and the 60 adjacent municipalities of the states of Mexico and Hidalgo

The oldest capital city in the Americas, it is is the largest Spanish-speaking city in the world.

6. Cairo, Egypt

Population in Urban Area: 21,323,000

Population in City Area: 8.1 m

36 Cairo
According to Population Stat, the current metro area population of Cairo in 2021 is 21,323,000, a 2.02% increase from 2020. Mohamed Abd El Ghan/Reuters

Cairo is the largest city in Africa and the Middle East.

7. Mumbai, India

Population in Urban Area: 20,668,000

Population in City Area:12,691,836

Mumbai Suburban district. The Mumbai Suburban district is a district of the state of Maharashtra in western India on February 16, 2015 in Mumbai, India.Mumbai is one of the main commercial hubs in the world by worldwide economic transactions. Photo by Frédéric Soltan/Corbis via Getty Images/Getty Images

Mumbai, which was official named Bombay until 1995, is the capital of the State of Maharashtra.

The city is India's financial and commercial centre, and the country's principal port on the Arabian Sea. Like other industrial megacities, it suffers with air and water pollution, as well as overcrowding.

8. Beijing, China

Population in Urban Area: 20,897,000

Population in City Area: 11,716,620

Beijing is the second largest city in China with over 20 million people in the urban area. Photo by GREG BAKER/AFP via Getty Images/Getty Images

About 21 million people live in Beijing, the capital of China, which makes it the world's most populous capital city.

9. Dhaka, Bangladesh

Population in Urban Area: 21,741,000

Population in City Area: 10,356,500

Dhaka, the capital of Bangladesh, has a population of 21.1 million people in the urban area and 10.3 million in the city iStock

Located on the banks of the Buriganga River, Dhaka is the capital and the biggest city of Bangladesh.

The city is the most densely populated on Earth, with nearly 37 people living in every square kilometer. The Greater Dhaka Area has a total population of more than 21 million.

Dhaka is also considered the rickshaw capital of the world, with the carts being the most popular method of transportation.

10. Osaka, Japan

Population in Urban Area:19,111,000

Population in City Area: 2,592,413

Aerial view of Osaka. View on the Osaka Bay and its port on March 28, 2015 in Osaka, Japan. Osaka is a megacity home to almost 19 million people in its urban area. Photo by Frédéric Soltan/Corbis via Getty Images/Getty Images

Japan's second largest city joins Tokyo on the list.

It is located in the Kansai region of the main island of Honshū, at the mouth of the Yodo River on Osaka Bay, relatively near to the ancient Japanese capital, Kyoto.

The port city is particularly known for its modern architecture and its street bars. Osaka is also home to the country's first Buddhist temple, Shi Tenno-ji.

11. New York, U.S.

Population in Urban Area: 18,823,000

Population in City Area:8.3 m

New York
The New York lower Manhattan skyline is seen as a backdrop for a traffic jam on an Expressway on May 15, 2020 in New York City. New York is the most populous city of the U.S. It became the most populous urbanized area in the world in the 1920s and the metropolitan area surpassed 10 million inhabitants in the early 1930s. Photo by JOHANNES EISELE/AFP via Getty Images/Getty Images

The first megacity in human history, New York is the most populous city in the United States. It also has the highest population density in the country, with over 10,194 people for every square kilometer.

According to Population Stat ,which uses sources from World Bank and United Nations, Census,New York City "is predicted to more than double in size by 2035, up to 20.8 million residents in the New York City urban area."

12. Karachi, Pakistan

Population in Urban Area: 16,459,000

Population in City Area: 11,624,219

40 Karachi
Karachi, Sindh province, Pakistan. With a population of 16 million, Karachi is the largest megacity in Pakistan Reuters

Pakistan economic and financial capital on the Arabian Sea. Karachi is the country's largest city and a major seaport, serving among others the landlocked country of Afghanistan.

A World Bank report from 2018, "Transforming Karachi into a Livable and Competitive Megacity," says that despite being a large city that is home to many, "Karachi has seen a substantial decline in quality of life and economic competitiveness in recent decades.

"Basic service delivery is very poor, with very low indicators for water supply, sanitation, public transport and public spaces. Pollution levels are high, and the city is vulnerable to disasters and climate change."

13. Buenos Aires, Argentina

Population in Urban Area: 15,258,000

Population in City Area:3m

Buenos Aires
Aerial view of 9 de Julio avenue and Plaza de la Republica square in Buenos Aires amid the Coronavirus pandemic on May 28, 2021. Photo by JUAN MABROMATA/AFP via Getty Images/Getty Images

Buenos Aires has a population of almost 3 million, with a metropolitan population of over 15 million. The capital and largest city in Argentina, it is located on the western shore of the Rio de la Plata .

With over 400 theaters, Buenos Aires is sometimes called the 'World's Capital of Theater'.

14. Chongqing, China

Population in Urban Area: 16,382,000

Population in City Area: 7,457,600

Chongqing, the largest Chinese city located on the upper Yangtze. Here the Jialing River (pea soup color) meets the Yangtze River. The largest rural city in China and one of the few megacities in China far from the coast . Photo by robert wallis/Corbis via Getty Images/Getty Images

A modern port city and a district in Central China, Chongqing is the largest municipality in southwest China with an area of 31,800 square miles (82,400 square kilometers).

15. Istanbul, Turkey

Population in Urban Area: 15,415,197

Population in City Area:14,804,116

Landscape photograph of the Istanbul waterfront and Bosphorus Strait, with the city skyline visible in the background, Istanbul, Turkey.The largest city in Turkey, Istanbul’s main economic sectors are tourism, entertainment, logistics, construction, finance, education, healthcare, automotive, and textile. Istanbul's 2021 population is now estimated at 15,415,197 Photo by Smith Collection/Gado/Getty Images/Getty Images

Istanbul, Turkey's largest city extends between Europe and Asia across the Bosphorus Strait.

Nearly two thirds of its residents live on the European side of the city, and the rest live on the Anatolian side.

16. Kolkata, India

Population in Urban Area: 14,974,000

Population in City Area: 4,631,392

Kolkata is the capital of the Indian state of West Bengal. Photo taken on June 20, 2016 in Kolkata (Calcutta), India. Kolkata is India's 3rd most populous metropolitan area, the largest urban area includes the suburbs and has a population of more than 14.9 million. Photo by Frédéric Soltan/Corbis via Getty Images/Getty Images

The capital and the largest city of the Indian state of West Bengal. Located on the banks of the Hooghly River, Kolkata is a city of commerce, transport, and manufacture, and the dominant urban centre of eastern India.

Formerly known as Calcutta, an Anglicized version of the Bengali name Kalikata.

17. Manila, Philippines

Population in Urban Area:14,159,000

Population in City Area:1,600,000

An aerial shot of Manila on December 23, 2013. A megacity with over 14 million inhabitants in the urban area, Manila faces many problems including overcrowding. Photo: TED ALJIBE/AFP via Getty Images/Getty Images

The capital of the Philippines, it is located on the island of Luzon and spreads along the eastern shore of Manila Bay. Manila faces problems with overcrowding which has resulted in housing shortage, congestion and air pollution.

18. Lagos, Nigeria

Population in Urban Area: 14,862,000

Population in City Area: 9 m

Lagos State,essentially comprising the city of Lagos, is one of the world's fastest growing megacities but according to the World Bank, they have a serious problem with air pollution, with a 2018 report estimating that air pollution caused more than 11,200 premature deaths in the Nigerian Capital. Photo: FLORIAN PLAUCHEUR/AFP via Getty Images/Getty Images

The second most populous city in Africa, its population continues to rise and according to Population Stat, "experts predict that by 2035, the city will have 24.4 million people and that by 2050, the population will double and make the city one of the top three largest in the entire world."

19. Rio de Janeiro, Brazil

Population in Urban Area: 13,544,000

Population in City Area: 6,023,699

Rio de Janeiro
Aerial view on "Lagoa Rodrigo de Freitas" and the city centre of Rio de Janeiro.Rio de Janeiro is the second-most populous city in Brazil with over 13 million inhabitants. Photo by Frédéric Soltan/Corbis via Getty Images/Getty Images

The second-most populous city in Brazil, Rio de Janeiro City is home to over 6 million people, about 35 percent of the population of Rio de Janeiro State.

Rio has the second biggest municipal GDP of Brazil estimated at about $201 billion USD.

20. Tianjin, China

Population in Urban Area: 13,794,000

Population in City Area: 11,090,314

China's fourth largest city, Tianjin is one of the biggest industrial and port cities in the country. Photo by TPG/Getty Images/Getty Images

After Shanghai and Beijing, it is the third largest municipality of China. It is also the main port of Northern China , often called "the gate of Beijing," and the biggest port created by man in China. The port occupies an area of 107 km2 and a quay with a length of 21.5 km

21. Kinshasa, DR Congo

Population in Urban Area:14,970,000

Population in City Area: 7,785,965

49 Kinshasa
Kinshasa, Democratic Republic of the Congo, West Africa. According to the World Bank 'Like many of the world’s megacities, Kinshasa faces many challenges. With nearly 15 million residents, the capital of the Democratic Republic of the Congo is known for its epic traffic jams, widespread poverty, unreliable electricity, decades of violent confrontation and an underlying vulnerability to floods, droughts, and other climate shocks'. Desirey Minkoh/AFP

Africa's third-largest metropolitan area after Cairo and Lagos, it is the world's largest Francophone urban area, French is the official language but Lingala, a Bantu language, is used as a lingua franca in the streets.

22. Guangzhou, China

Population in Urban Area: 13,635,397

Population in City Area:11,071,424

China's southern Guangdong province on September 17, 2021. Guangzhou's 2021 population is now estimated at 13,635,397. Photo by NOEL CELIS/AFP via Getty Images

One of China's three largest cities.

A major port, it was "part of the Silk Route of the Sea" from the third century, during the reign of the Qin dynasty. The main part of the city is situated on the north bank of the Pearl River, about 120 km north-northwest of Hong Kong .

23. Los Angeles, U.S.

Population: 12,459,000

Population in City Area: 3.9 m

los angeles courthouse shooting
The Los Angeles skyline is seen on April 4, 2020. Mario Tama/Getty Images

The Los Angeles metropolitan area is the second-largest metropolitan area in the nation after New York. Located near the Pacific coast in Southern California, most of the population of the Los Angeles metropolitan area is centralized in the City of Los Angeles.

24. Moscow, Russia

Population in Urban Area: 12,593,000

Population in City Area: 10,381,222

An aerial view of the Staraya square and Presidential Administration building , on March,14,2021, in Moscow, Russia.The Moscow megalopolis, that includes Moscow and the Moscow Region, ranks among the largest megacities in the world. Photo by Mikhail Svetlov/Getty Images/Getty Images

The capital of Russia and the northernmost major city in the world. Moscow, is the second most populated city in Europe, after Istanbul in Turkey.

The Moscow metro system is the third busiest in the world and shuttles up to 6-million people on a daily basis.

25. Shenzhen, China

Population in Urban Area: 12,592,000

Population in City Area: 10,358,381

China Skyscraper Evacuated After More Shaking
Shenzhen is also known as China's Silicon Valley, as many Chinese tech-giants are headquartered there. STR/AFP via Getty Images

Located next to Hong Kong, it is the home of the most high-rise buildings in China. Shenzhen wasn't technically a city until 1979 but only 42 years later, it is the largest economy in China's Greater Bay Area.

According to Statista, Shenzhen is "one of the fastest growing cities in China. Based on estimates, the population of Shenzhen is expected to reach over 15 million by 2035. This rapidly growing city is attracting an increasing number of young Chinese, who want to start and grow their careers."

The population estimates and projections come from the U.N, World Urbanization Prospects and Macrotrends data.