Famous for his spirited role in the Gurdwara Reform movement, was born the son of Teja Singh in 1874 at the village of Jhabbar, in Sheikhupura district, now in Pakistan. His grandfather, Mangal Singh, had served as a commandant in Maharaja Ranjit Singh’s army. Kartar Singh had no formal education, but somewhat late in life He went through a course of Sikh religious learning and trained as a missionary at Khalsa Updeshak Mahavidyala, Gharjakh, which he attended from 1906 to 1909. Upon completing the course, he took up preaching.
In 1912, he set up Khalsa Diwan Khara Sauda Bar at Gurdwara Sachcha Sauda, Chuharkana. He also opened in the town in 1917 a middle school. In 1919, Kartar Singh took active part in anti-government demonstrations and addressed meetings protesting against the Jallianvala Bagh massacre. For this he was arrested and was, on trial, sentenced to death on 22 May 1919. The punishment was reduced on 30 May 1919 to transportation for life. He was, however, released from Andamans jail in March 1920 in the wake of royal clemency.
In early October 1920, Kartar Singh led a jatha of Sikh volunteers to Sialkot to liberate Gurdwara Babe di Ber from the control of a corrupt mahant or custodian. The shrine was taken possession of and a committee of lay Sikhs was formed to manage it, with Baba Kharak Singh as president. This was the beginning of the Gurdwara Reform movement. Kartar Singh Jhabbar, along with Teja Singh Bhuchchar, got the Akal Takht released on 12 October 1920. Teja Singh was appointed jalhedar or provost of the Takht. Jhabbar was included in the 9 member committee set up for the management of the Golden Temple. He continued to be in the vanguard of reformist Sikhs’ campaign for liberating historical shrines. The more important ones he helped to take possession of were Gurdwara Panja Sahib (November 1920), Gurdwara Sachcha Sauda (December 1920), Gurdwara Tarn Taran (26 January 1921), and Gurdwara Guru ka Bagh (31 January 1921).
Following the possession of Gurdwara Janam Asthan at Nankana Sahib, the birthplace of Guru Nanak, where about 150 reformist Sikhs had been murdered by the mahant and his men on 20 February 1921, Kartar Singh was arrested on 11 March 1921 and remained in jail for about six months. He was rearrested in June 1924 and sent to Campbellpore jail. In September 1925 he was transferred to Multan jail and in April 1926 to Rawalpindi. He remained in custody for more than four years and was released in December 1928.
After the control of the gurdwaras was, by government legislation of 1925, made over to a representative board of the Sikhs, Kartar Singh retired to a comparatively quiet life at his village. In January 1933 he faced a charge of murder following a clash which took place at Nankana Sahib over the possession of a portion of the Gurdwara land, but was acquitted by the court. In 1937, he led a jatha to Kot Bhai Than Singh and convened, in defiance of the orders of the local Muslim chieftain, a Sikh divan. After the partition of Punjab in August 1947, Kartar Singh came over to what was then designated as East Punjab, and settled down at the village of Habri, in Karnal district, where he died on 20 November 1962.