Kuala Lumpur (KL), officially the Federal Territory of Kuala Lumpur, is the capital city and a federal territory of Malaysia. It is the most populous city in the country, covering an area of 243 km² (94 sq mi) with a census population of 2,075,600 as of 2024^[update]. Greater Kuala Lumpur, also known as the Klang Valley, is an urban agglomeration of 8.8 million people as of 2024. It is among the fastest growing metropolitan regions in Southeast Asia, both in population and economic development.

The city serves as the cultural, financial, tourism, political and economic centre of Malaysia. It is also home to the Malaysian parliament (consisting of the Dewan Rakyat and the Dewan Negara) and the Istana Negara, the official residence of the monarch (Yang di-Pertuan Agong). Kuala Lumpur was first developed around 1857 as a town serving the tin mines of the region, and important figures such as Yap Ah Loy and Frank Swettenham were instrumental in the early development of the city during the late 19th century. It served as the capital of Selangor from 1880 until 1978. Kuala Lumpur was the founding capital of the Federation of Malaya and its successor, Malaysia. The city remained the seat of the executive and judicial branches of the Malaysian federal government until these were relocated to Putrajaya in early 1999. However, some sections of the political bodies still remain in Kuala Lumpur. The city is one of the three Federal Territories of Malaysia, enclaved within the state of Selangor, on the central west coast of Peninsular Malaysia.

Since the 1990s, the city has played host to many international sporting, political and cultural events, including the 1998 Commonwealth Games, 2001 Southeast Asian Games, 2017 Southeast Asian Games, Formula One, Moto GP and 1997 FIFA World Youth Championships. Kuala Lumpur has undergone rapid development in recent decades and is home to the tallest twin buildings in the world, the Petronas Towers, which have since become an iconic symbol of Malaysian development. Kuala Lumpur is well connected with neighbouring urban metro regions such as Petaling Jaya via the rapidly expanding Klang Valley Integrated Transit System. Residents of the city can also travel to other parts of Peninsular Malaysia as well as to Kuala Lumpur International Airport (KLIA) via rail through Kuala Lumpur Sentral station.

Kuala Lumpur was ranked the 6th most-visited city in the world on the Mastercard Destination Cities Index in 2019. The city houses three of the world's ten largest shopping malls. Kuala Lumpur ranks 70th in the world and the second in Southeast Asia after Singapore for the Economist Intelligence Unit's Global Liveability Ranking and ninth in ASPAC and second in Southeast Asia after Singapore for KPMG's Leading Technology Innovation Hub 2021. Kuala Lumpur was named World Book Capital 2020 by UNESCO. In 2025, Kuala Lumpur was ranked second for the best outstanding city in Southeast Asia, after Singapore, and 79th in the world by the Oxford Economic Papers' Global Cities Index.

Kuala Lumpur means "muddy confluence" in Malay: kuala is the point where two rivers join, or an estuary, and lumpur means "mud". One suggestion is that it was named after Sungai Lumpur ("muddy river"); in the 1820s, a place named Sungei Lumpoor was said to be the most important tin-producing settlement on the Klang River. However, Kuala Lumpur lies at the confluence of the Gombak and Klang rivers and therefore should be called Kuala Gombak, since the kuala is typically named after the river that joins a larger river or the sea. Some have argued that Sungai Lumpur extended to the confluence, therefore, the point where it joined the Klang River would be Kuala Lumpur, although this Sungai Lumpur is said to be another river joining the Klang River 1.5 kilometres (1 mile) upstream from the Gombak confluence, or perhaps located to the north of the Batu Caves area.

It has also been proposed that Kuala Lumpur was originally named Pengkalan Lumpur ("muddy landing place"), in the same way that Klang was once called Pengkalan Batu ("stone landing place"), but became corrupted into Kuala Lumpur. Another theory says that it was initially a Cantonese word, lam-pa, meaning "flooded jungle" or "decayed jungle". There is no firm contemporary evidence for these suggestions other than anecdotes, however. The name may also be a corrupted form of an earlier forgotten name.

Sultanate of Selangor 1857–1974
Federated Malay States 1895–1942; 1945–1946
Empire of Japan 1942–1945
Malayan Union 1946–1948
Federation of Malaya 1948–1963
Malaysia 1963–present

Official account considers Kuala Lumpur to have been founded by the Malay Chief of Klang, Raja Abdullah, who sent Chinese miners into the region to open tin mines in 1857, although it is unclear who the first settlers were since there were likely settlements at the Gombak-Klang river confluence before that in the 1820s. Chinese miners were known to be involved in tin mining up the Selangor River in the 1840s about 16 kilometres (10 miles) north of present-day Kuala Lumpur, and Mandailing Sumatrans led by Raja Asal [ms] and Sutan Puasa were also involved in tin mining and trade in the Ulu Klang region before 1860, and Sumatrans may have settled in the upper reaches of Klang River in the first quarter of the 19th century, or possibly earlier. Kuala Lumpur was originally a small hamlet of just a few houses and shops at the confluence of the Sungai Gombak and Sungai Klang (Klang River). Kuala Lumpur became established as a town c. 1857, when Raja Abdullah bin Raja Jaafar, aided by his brother Raja Juma'at of Lukut, raised funds from Malaccan Chinese businessmen to hire Chinese miners from Lukut to open new tin mines there. The miners landed at Kuala Lumpur and continued on foot to Ampang, where they opened the first mine. Kuala Lumpur was the furthest point up the Klang River to which supplies could conveniently be brought by boat and therefore became a collection and dispersal point serving the tin mines.