A significant shift in global urban demographics has occurred, with Jakarta, Indonesia, officially becoming the world's largest city with a staggering population of 42 million people. This announcement, made by UN researchers in November 2025, ends Tokyo's 25-year reign at the top.
The Indonesian capital's rapid growth presents a stark contrast to London's more modest population of 9.8 million, highlighting the dramatic scale of urban expansion in Asia.
Jakarta's Scale and Infrastructure
To manage its immense population, Jakarta has developed substantial public transport networks. The city boasts the TransJakarta bus rapid transit system, frequently cited as the world's longest and largest of its kind. This network spans an impressive 251 kilometres and facilitates over one million passenger journeys every day.
For rail travel, Jakarta is served by the Jakarta MRT and the Jabodebek LRT, which are its developing rapid train systems and the closest equivalents to the London Underground.
The Challenges of Massive Growth
This immense scale comes with significant urban challenges. Residents of Jakarta routinely contend with severe traffic congestion, high pollution levels, and frequent flooding.
The difficulties are so profound that in 2019, the Indonesian government announced a plan to move the national capital to Borneo. However, this ambitious project has reportedly fallen behind schedule and has faced challenges in attracting sufficient investment.
A Global Trend Towards Urbanisation
This change in the world's largest city is part of a broader global pattern. According to UN research, cities are now home to 45% of the planet's 8.2 billion people. Since 1950, the number of people living in urban areas has more than doubled.
Looking ahead to 2050, two-thirds of all global population growth is projected to occur in cities. The rise of megacities—urban areas with 10 million or more inhabitants—is a defining feature of this century. More than half of these megacities are located in Asia, which is also home to nine of the world's ten most populous cities.
By 2050, the number of megacities is expected to surge to 37. Cities like Addis Ababa, Dar es Salaam, Hajipur, and Kuala Lumpur are projected to join the ranks of those surpassing the 10-million-resident mark.
Tokyo's Population Decline
For the former title-holder, Tokyo, the story is one of demographic change. The city has been experiencing slowing population growth, with government data from 2024 showing the number of Japanese nationals fell by more than 900,000 in a single year.
Tokyo's peak population was recorded in 2009 at nearly 12.7 million, but it has been on a gradual decline for 16 consecutive years. The city's government has attempted to counter this trend with initiatives such as childbirth and housing subsidies, and by encouraging paternity leave.
Despite these efforts, the decline continues. In 2024, Japan recorded its lowest number of births since 1969, at just 687,689, while nearly 1.6 million deaths were recorded in the same period.
The World's Largest Cities in 2025:
- Jakarta, Indonesia – 42 million
- Dhaka, Bangladesh – 37 million
- Tokyo, Japan – 33 million
- New Delhi, India – 30 million
- Shanghai, China – 30 million
- Guangzhou, China – 28 million
- Cairo, Egypt – 26 million
- Manila, Philippines – 25 million
- Kolkata, India – 23 million
- Seoul, South Korea – 22 million
