Una's history is deeply intertwined with the broader Kangra region and the neighboring state of Punjab. For much of its early history, the area was ruled by the Katoch dynasty of Kangra. It is also a site of great spiritual significance; the city was heavily influenced by the Bedi family, descendants of Guru Nanak Dev Ji, who settled in Una and helped establish it as an important religious center. The historical fort and properties associated with the Bedi family remain significant cultural landmarks.
During British colonial rule, Una was administered as a tehsil within the Hoshiarpur district of the Punjab Province. It remained a part of Punjab after India's independence in 1947.
A major turning point in the city's modern history occurred with the Punjab Reorganisation Act of 1966. On November 1, 1966, Una was transferred from Punjab to the newly formed union territory (and later state) of Himachal Pradesh. Eventually, recognizing the need for better local administration, the Government of Himachal Pradesh carved Una out as a distinct district on September 1, 1972, with the city of Una serving as its administrative headquarters.