Sheikh Jābir was the third son of Sheikh Aḥmad al-Jābir al-Sạbāḥ, who ruled Kuwait from 1921 to 1950. Beginning in the late 1940s he held a number of important public positions, including ministries in the government overseeing financial and economic affairs. When Iraq claimed sovereignty over newly independent Kuwait in 1961, he led a delegation to the Arab League to negotiate a settlement. He became prime minister in November 1965, and the following year he was formally designated crown prince and heir apparent to his cousin Emir Sheikh Sạbāḥ al-Salim al-Sạbāḥ. By the early 1970s the emir, suffering from poor health, had handed over most of the government operations to Sheikh Jābir, and upon Sheikh Sạbāḥ's death, on December 31, 1977, Sheikh Jābir became emir.

Early in his rule Sheikh Jābir stressed unity among Arab countries, but he soon found his policies caught in the cross fire of the Iran-Iraq War (1980–88). He was also forced to deal with internal dissent, particularly from Kuwait's Shīʿite minority, and with opposition from the National Assembly (parliament). In 1986 he dissolved the parliament and imposed press censorship, which led to periodic protests against the economic and political power of the Sạbāḥ family. When Iraqi troops invaded Kuwait in August 1990, Sheikh Jābir escaped to Saudi Arabia, where he lived in exile until his return in March 1991. Pressure for reform continued, and in elections held in October 1992 opponents won a majority of seats in the National Assembly. In elections in 1996, however, progovernment forces gained some of the ground they had lost, but in May 1999 Sheikh Jābir once again dissolved the parliament. Although antigovernment sentiment was high in the new parliament, elected in July, the opposition was divided and Sheikh Jābir retained his authority. The emir was noted for his public support for the rights of women (against the wishes of more conservative elements in the country); in 1999 his decree to grant women the right to vote was rejected, but in 2005 women were extended the right to stand and vote in parliamentary elections. In 2001 Sheikh Jābir suffered a stroke and thereafter carried out virtually no public activities.