He began to open Bhutan to the outside world, began modernization, and took the first steps toward democratization. Upon succeeding his father, Jigme Wangchuck, on October 27, 1952, Jigme Dorji Wangchuck put an end to feudalism and slavery and released all remaining serfs. He encouraged certain modern inventions to assist the local peasantry and introduced wheeled vehicles, where previously the transportation of crops and people was done manually. He established a High court and reorganized the judicial system. In 1953, he established the Tshogdu or National assembly - Bhutan’s first unicameral Parliament. He established the Royal Advisory Council in 1963. During his reign Bhutan’s first planned economic development plan was drafted. In 1961, a five year economic development plan was launched for the years 1961-1966. Bhutan is still following this economic development plan. He created Bhutan’s first Council of Ministers in 1968. In 1963, Bhutan joined the Colombo Plan. During his 20-year reign, 1770 km of roads were constructed, the number of schools rose to 102 and 6 hospitals were established. In 1971, he set up a Planning Commission. Bhutan was admitted to the United Nations in 1971.
In 1950, the People's Republic of China occupied Tibet, a country with which Bhutan had a long-established relationship. This encouraged the king to foster stronger ties with foreign nations, especially India, and culminated with Bhutan joining the United Nations in 1971. At the same time, he empowered the National Assembly to remove him or any of his successors with a two-thirds majority.
Jigme Dorji Wangchuck suffered his first heart attack at the age of twenty. He made frequent visits overseas for medical treatment, dying in Nairobi, Kenya, while receiving medical treatment, in 1972. Jigme Singye Wangchuck, his son, succeeded him. He was married to Queen Ashi Kelzang Chhoedon Wangchuck.