It lies south of the Colombo Municipal Council area and is separated from it by the Dehiwala canal which forms the northern boundary of DMMC.

Its southern limits lie in Borupana Road and the eastern boundary is Weras Ganga with its canal system and it includes some areas to its east (Pepiliyana, Gangodawila and Kohuwala).

It comprised a number of villages such as Pepiliyana Nedimala, Attidiya and Kalubowila, while Ratmalana and areas south of Dehiwala were together one large expanse of marshland, and scarcely populated.

[4] During the Portuguese occupation, the Kingdom of Kotte was ruled by king Don Juan Dharmapala, and it encompassed the above-mentioned villages.

Early records also indicate that in the year 1510 AD the village of “Galkissa” is mentioned and named after the rocky mound (Lihiniyagala) protruding into the Bay.

With the arrival of the Dutch in the early seventeenth century, a more organised administrative structure was in place, whereby a broad-based taxation and legal system evolved.

When the second Governor of Ceylon, Sir Thomas Maitland, acquired land at "Galkissa" (Mount Lavinia), he decided in 1806 to construct a personal residence there.

Maitland fell in love with Lovina Aponsuwa, a local mestiço dancer, and continued a romantic affair with her until he was recalled to England in 1811.

Due to rapid urban growth and for administrative reasons this area was extended and divided into 19 wards in 1959 and given Municipal status.

A significant feature is the large extent of wetlands around the Weras Ganga (river) and Bolgoda Lake, the two major water bodies.

Lying in the wet zone, the Dehiwala-Mount Lavinia area receives an average annual rainfall between 2,000–3,000 mm (79–118 in) mainly during the southwest monsoon and the intermonsoon periods.

There are 2 Divisional Secretaries in the Dehiwala-Mount Lavinia area The Sri Lanka Police, the main law enforcement agency of the island, liaise with the municipal council, but is under the control of the Ministry of Defence of the central government.

Dehiwala and Mount Lavinia lie along the Galle Road artery in the West of the city, which runs along the coast to the south of the country.