The Unionist Party, also known as the Unionist Muslim League was an Indian political party that was established in the province of Punjab during the era of the rule of the British Empire in India. The Unionist Party primarily stood for the interests of the landed gentry and landlords of Punjab that comprised of Hindus, Sikhs and Muslims. The members of the Unionist Muslim League dominated the political scenario in Punjab from the period of the First World War to the autonomy of South Asia and the Partition of Indian into the Union of India and the Dominion of Pakistan in the year 1947.

The Unionist Party was formed as a secular party that represented the interests of the large feudal classes and gentry in Punjab. The party was founded by Sir Chhotu Ram, Sir Fazli Husain and Sir Sikandar Hyat Khan. Even though most of the members of the Unionist Party were Muslims, several Sikhs and Hindus supported and participated in the Unionist Muslim League as well. The Unionist Party did not have a mass based approach, unlike the Indian National Congress Party and various other political parties that existed at the time. The members of the Party also supported the British government of India, and contested elections for the Punjab Legislative Council and the central Legislative Council, in contrast with the Congress Party and the Muslim League. Consequently, the Unionist Party conquered the provincial legislature for several years. This allowed an elected provincial government to operate when other provinces were administered by direct rule of the British.

The Muslim members of the Unionist Party or Unionist Muslim League shared several general viewpoints with the Muslim League and adopted almost similar agenda and policy for national issues and interests. However the Unionist Party was practically an independent political party during the 1920s and 1930s, while the when the Muslim League was detested and segregated into feuding groups. Sir Sikandar, the Unionist leader, became the most influential and popular politician in Punjab during that era. He prevented both Muhammad Ali Jinnah, the president of the Muslim League, and Sir Muhammad Iqbal from acquiring the support of a majority of Punjabi Muslims.

However, The Unionist Party maintained a close association with the All India Muslim League during the early 1940s. Sir Sikandar was amongst the supporters of the Pakistan Resolution which was passed on 23rd March 1940 in Lahore. It called for an independent Muslim state or territory in a larger Indian confederation. This eventually grew into the demand for the formation of an independent Dominion of Pakistan. After the death of Sir Sikandar in the year 1942, Sir Malik Khizar Hayat Tiwana became the premier. Under his leadership, the Unionist Muslim League or the Unionist Party waned in popularity and could not match up with the increasing influence of Jinnah.

As the demand for Pakistan became more intense, political allegiances in the Punjab were determined on religious basis. With the partition of the former British India in August 1947 into 2 independent factions, the Union of India and the Dominion of Pakistan, Punjab was itself divided between the 2 newly formed countries. The diverse pan provincial organisation of the Unionist Party was ruined with the integration of Muslim Unionists themselves into the Muslim League. Eventually the party ceased to exist in the sovereign Dominion of Pakistan.