The name Kelaniya is believed to derive from the Kelani River, which flows serenely beside the town. In Sinhala, “Kelani” is thought to mean “pure” or “sacred,” a fitting tribute to the river’s spiritual and ecological importance. The suffix “-ya” denotes a place, making Kelaniya the “place of the sacred Kelani.”

According to the ancient chronicle Mahavamsa, the Buddha visited Kelaniya during both his first and third visits to Sri Lanka, over 2,500 years ago. During his third visit, he was invited by King Maniakkhika, ruler of the Naga people, to settle a dispute between two warring Naga chieftains. After resolving the conflict, the Buddha was offered a jeweled throne, which he used while preaching. That throne is believed to be enshrined within the Kelaniya Stupa, making the site one of the most sacred in the country.

As of the most recent data, Kelaniya town has a population of approximately 145,543 residents, spread across an area of 20 square kilometers, resulting in a population density of 7,277 people per km². The community is predominantly Sinhalese Buddhist, with vibrant minorities of Sri Lankan Moors (Muslims), Sri Lankan Tamils, and Christians, reflecting the town’s pluralistic heritage.

The median age is around 34 years, with a nearly even gender split—50.7% female and 49.3% male. The town’s demographic profile is youthful, educated, and increasingly engaged in both traditional livelihoods and modern service industries.