Hamid Gul was born in Sargodha, Punjab, and was commissioned as a Lieutenant in the Pakistani Army in 1954 in the Armored Corps. He was a Tank Commander during the 1965 war with India and won the Sitara-i-Jurat.

Right after winning the war of 1965 he was rose to be the Director General of Military Intelligence (DGMI) under General Muhammad Zia-ul-Haq who then nominated him to be the ISI chief succeeding General Akhtar Abdur Rahman in March 1987.

During his tenure as ISI chief in 1988, General Gul successfully gathered right-wing politicians and helped them create Islami Jamhoori Ittehad, a religio-political conservative coalition of that time.

In Islamabad, General Hamid Gul asked that Iran should explain its bona fides regarding the pact signed with India to jointly counter terrorism. According to him, "Iran should come clear on the nature of agreement with India. Otherwise this will create doubts and apprehensions in Muslim Ummah that Iran helps RAW in putting down Kashmir jihad". He also added that in case doubts about the agreement came true and Iran was seen as working with India against "Kashmir freedom struggle", then it will be concluded that the country also supports Mossad, Israeli external intelligence agency.

He was later replaced as the ISI commander by PM Benazir Bhutto in May 1989 and Gul was transferred as the commander, II Corps in Multan. In this capacity, Gen. Hamid Gul conducted the Zarb-e-Momin military exercise in November-December 1989, the biggest Pakistani Armed Forces show of muscle since 1971 Indo-Pakistani War, which was also a great success.
General Asif Nawaz upon taking the reins of Pakistan Army in August 1991, had Gul transferred as the DG Heavy Industries Taxila. A menial job compared to Gul's stature, Gul refused to take the assignment, an act for which he resigned from the army by saying that “I am not born to serve as a factory manager, I am general and will die as a general”.