Thimphu's history as a prominent center dates back to the 13th century when Phajo Drugom Shigpo, a Tibetan lama, founded the Dechen Phodrang Lhakhang on a ridge above the valley. In 1641, Shabdrung Ngawang Namgyal, the unifier of Bhutan, acquired the valley's fortress and renamed it Tashichho Dzong ("Fortress of the Glorious Religion").
For centuries, the Thimphu valley was primarily a scattering of rural hamlets. Bhutan's early capitals were situated in Punakha and Wangdue Phodrang. However, in 1955, the Third King of Bhutan, Jigme Dorji Wangchuck, declared Thimphu the year-round capital of the kingdom. It was officially established as such in 1961, initiating a wave of planned development.
During the 1960s, with the support of international allies, particularly India, Thimphu began its transformation from a quiet agrarian valley to a modern capital. Roads were paved, schools established, and government infrastructure constructed. In 2008, Thimphu was the site of the historic signing of Bhutan's Constitution, officially transitioning the nation from an absolute to a constitutional monarchy. Since then, the city has experienced a wave of rural-to-urban migration, drastically evolving its cultural landscape and expanding its footprint down the valley.