The former ISI chief suffered a brain hemorrhage and was shifted to the Combined Military Hospital in Murree in critical condition, said his daughter Uzma Gul.
Prime Minister Muhammad Nawaz Sharif has expressed his condolences.
Born in Sargodha on Nov 20, 1936, he joined the army in 1954 and was commissioned in the army in 1956.
During the 1965 war he was a tank commander and was awarded Sitara-i-Jurat for bravery.
Known for his hardline views, Gen. Gul headed the powerful military intelligence agency from 1987 to 1989 when Afghanistan was in a state of tumult after defeat of the Soviet occupation forces. His policy on the Afghan jihad earned him supporters and critics.
General Gul supported the armed insurgency in Afghanistan and Indian-administered Kashmir.
For more than two decades after he retired in 1992, Gen Gul frequently appeared on global news media often blaming Washington and Delhi for violence and instability in Pakistan.