Jakarta, the capital of Indonesia, has officially become the world’s most populous city, with a population nearing 42 million, according to the latest World Urbanization Prospects 2025 report released by the UN Department of Economic and Social Affairs (UN DESA).
This position was previously held by Tokyo, which now ranks third with around 33 million residents. Dhaka, the capital of Bangladesh, takes second place with nearly 40 million people.
This report marks the first major revision since the 2018 edition, when Tokyo still topped the list and Jakarta had not even entered the top 10. The dramatic surge highlights the rapid and intense pace of urbanization across Asia.
Global Urbanization Accelerates
Globally, the world is entering an unprecedented phase of urban growth. The UN reports that 45 percent of the planet’s 8.2 billion people now live in cities, a sharp increase from 1950, when only 20 percent of the world’s 2.5 billion residents lived in urban areas.
This trend is expected to continue. By 2050, two-thirds of global population growth will occur in cities, while the remaining one-third will take place in small cities or semi-urban regions.
The Megacity Era: Asia Leads the Way
The phenomenon of the “megacity”, cities with more than 10 million inhabitants, is a central focus of the UN report. In 1975, the world had only eight megacities. By 2025, that number will soar to 33, with 19 of them located in Asia.
By 2050, the number of megacities is projected to rise further to 37, with potential new entrants including Addis Ababa (Ethiopia), Dar es Salaam (Tanzania), Hajipur (India), and Kuala Lumpur (Malaysia), all expected to surpass the 10-million threshold.
However, the UN emphasizes that small and medium-sized cities will continue to house the majority of the world’s population, and are growing even faster than megacities.
Of the 12,000 cities analyzed, 96 percent have fewer than one million residents, and 81 percent have under 250,000. By 2050, the total number of cities worldwide is expected to exceed 15,000, with most of them remaining small in size.
How Did Jakarta Become the Most Densely Populated City?
Jakarta’s extreme population density is not driven solely by birth rates. According to the UN and several studies, urbanization is the primary force behind its growth. The city continues to attract large numbers of migrants from across the country, even though its own birth rate is relatively low.
One study notes that Jakarta's population density has reached 22,000 people per square kilometer. This extreme density fuels worsening traffic congestion, high vehicle fuel consumption, and ultimately contributes to deteriorating air quality.
Jakarta also faces a dangerous combination of environmental pressures and climate change. Uncontrolled groundwater extraction has caused significant land subsidence, making many areas increasingly prone to flooding, especially as extreme rainfall becomes more frequent due to climate change.
Capital Relocation and Jakarta’s Future
In 2019, the Indonesian government announced plans to relocate the country’s capital to Nusantara (IKN), a new city being developed in East Kalimantan. The US$32 billion project was initially slated for inauguration in 2024, but the target has since been pushed back to 2028, when it is expected to become Indonesia’s administrative center.
However, the report emphasizes that there is no guarantee the capital relocation will immediately ease Jakarta's demographic and ecological pressures. Massive urbanization, the region’s economic centrality, and ongoing migration patterns mean that the impact of the move may take a long time to become evident.
A Global Snapshot: Not All Cities Are Growing
One interesting finding from the UN report is that not all cities follow the same growth trajectory. Some are shrinking even though their countries continue to grow demographically.
Two major cities, Mexico City and Chengdu in China, have recorded population declines. This phenomenon highlights how migration trends, economic shifts, and regional characteristics shape a city’s development path.
Jakarta at the Center of Global Urbanization
The UN’s 2025 report offers both insight and warning about the future of major cities worldwide. With its new status as the world’s most populous city, Jakarta has become a symbol of the profound transformations occurring in the era of global urbanization, while also standing as a clear example of the challenges facing modern urban governance: density, mobility, pollution, and the growing threat of climate change.
