Was born at Kapurthala on 15 April 1849. His father, Basava Singh, a native of Chandhar village, in Gujranwala district (now in Pakistan), served as a cook in the royal household of Kapurthala. Gurmukh Singh was a promising child and caught the fancy of their master, Prince Bikrama Singh, who began taking personal interest in his upbringing and education.

After he had finished school at Kapurthala, Gurmukh Singh was admitted to Government College, Lahore. He, like his patron Bikrama Singh, felt concerned about the state of Sikh society, and when Sri Guru Singh Sabha was set up at Amritsar in 1873, he left off his studies without graduating with a view to propagating reform. He was instrumental in having Punjabi included, in 1877, in the curriculum at Oriental College, Lahore. He himself was appointed the first lecturer to teach the language. Bhai Gurmukh Singh did not let his academic duties obstruct his Singh Sabha work. He was secretary of Sri Guru Singh Sabha, Lahore, which he had helped to establish in 1879. Likewise, he was the first chief secretary of Khalsa Diwan, Amritsar, founded four years later.

Gurmukh Singh's zeal for radical reform brought him into conflict with the president of the Diwan, Baba Khem Singh. During the Baisakhi session of the Diwan in April 1884, Baba Khem Singh, being a descendant of Guru Nanak, sat on a special cushioned seat in the presence of Guru Granth Sahib. This was resented by Gurmukh Singh, who said that none could claim such a privilege in a Sikh assembly where all sat together as equals, without any distinctions of class or status. In the same meeting he opposed the proposal sponsored by the Rawalpindi Singh Sabha, which was under the influence of Baba Khem Singh, that to enable non-initiated Sikhs to enrol as members the name Singh Sabha be changed to Sikh Singh Sabha. In May 1885, a book entitled Khurshid Khalsa published by the brothers Bava Nihal Singh and Sarmukh Singh of Chhichhrauli, followers of Baba Khem Singh. It contained statements judged to be contrary to Sikh tenets. The book also pleaded for the reinstatement of Maharaja Duleep Singh as the ruler of the Punjab and the appointment of Thakur Singh Sandhahvalia as his prime minister.

Bhai Gurmukh Singh proposed that the Khalsa Diwan should publicly dissociate itself from the views expressed in the book. The differences came to a head at the Divali session of the Diwan, when a representative of Raja Bikram Singh of Faridkot surprised Bhai Gurmukh Singh by reading out a statement of charges against him. Bhai Gurmukh Singh resigned from the Diwan, with representatives of several Singh Sabhas following suit. A schism in the Diwan was now inevitable. Bhai Gurmukh Singh and his supporters called a meeting at Lahore on 10-11 April 1886 and formed a separate Khalsa Diwan, with Sardar Attar Singh of Bhadaur as president and Bhai Gurmukh Singh as chief secretary. The Amritsar faction retaliated by getting Bhai Gurmukh Singh excommunicated through a resolution passed in April 1887 and issued under the seal of the Golden Temple.

The Khalsa Diwan Lahore, which enjoyed the support of the majority of the Singh Sabhas, however, ignored the resolution. Bhai Gurmukh Singh continued in office. The death, in May 1887, of his patron and benefactor, Kanvar Bikrama Singh, meant a great personal loss to him; yet he did not slacken the pace of his activity. By now he had reclaimed two very energetic persons - Bhai Jawahir Singh and Giani Ditt Singh - from the influence of Arya Samaj, and inducted them into the Singh Sabha. The three of them working as a closely-knit team were henceforth the life and soul of the Khalsa Diwan, Lahore. They preached assiduously through press and platform the message of reform and awakening among the Sikh masses.

Education was considered to be the key to modern awakening and this was one of Bhai Gurmukh Singh's persistent concerns. As early as June 1882, a proposal had been made to set up a Sikh college. Soon after the establishment of the Khalsa Diwan Amritsar in April 1883, Bhai Gurmukh Singh formally placed the motion before it at its special meeting held in June 1883. It was taken up more vigorously later by the Khalsa Diwan Lahore. Bhai Gurmukh Singh enlisted the co-operation of some government officials, and a Khalsa College Establishment Committee was constituted with Colonel W.R.M. Holroyd, Director of Public Instruction, as chairman and Mr William Bell, a professor of Government College, Lahore, as secretary. The efforts of Bhai Gurmukh Singh and other leaders of the Singh Sabha bore fruit and the cornerstone of the college was laid at Amritsar on 5 March 1892 by Sir James B. Lyall, Lieutenant-Governor of the Punjab.

To disseminate widely the Singh Sabha creed, Gurmukh Singh launched, one after another, the Gurmukhi Akhbar (1880), the Vidyarak (1880), the Khalsd (1885), the Sudhararak (1886) and the Khalsa Gazette (1886). These were among the first newspapers and periodicals in Punjabi, and besides serving the cause of religious reform, they gave birth to a new literary idiom in the language. Bhai Gurmukh Singh also published, in 1889, a jantri or almanac, called Gur Baras, the years of the Lord, the first of its kind in Punjabi in Gurmukhi script. Another work by him is Bharat di Itihaas, a history of India in Punjabi. He also wrote Gurbani Bhavarth, a glossary in simple Punjabi to make the gurbani of the Guru Granth Sahib intelligible to the common man. The work, however, remained unpublished.

Bhai Gurmukh Singh married twice, but had no children. He died of a heart attack on 24 September 1898 at Kandaghat, in Shimla Hills, where he had gone to see the Maharaja of Dhaulpur for a donation for Khalsa College, Amritsar.

Source: Encyclopaedia of Sikhism, Harbans Singh