He formed the Jamiat-e Islami (Islamic Society) at the university which attracted then-students Gulbuddin Hekmatyar and Ahmad Shah Massoud, both would eventually become the two leading commanders of the Afghan mujahideen in the Soviet–Afghan War from 1979.

After the Taliban government was toppled during Operation Enduring Freedom, Rabbani returned to Kabul and served briefly as president from 13 November to 22 December 2001, when Hamid Karzai was chosen as his succeeding interim leader at the Bonn International Conference.

As suggested by the Afghan parliament, Afghanistan's President Hamid Karzai gave him the title of "Martyr of Peace".

[3] His son Salahuddin Rabbani was chosen in April 2012 to lead efforts to forge peace in Afghanistan with the Taliban.

[5] In order to enhance himself, Rabbani went to Egypt in 1966, and he entered the Al-Azhar University in Cairo where he developed close ties to the Muslim Brotherhood leadership.

He resumed his position at the university and became closely associated with his fellow professor, Gholam Mohammad Niazi, whom he served as secretary in 1969 and 1970.

Rabbani returned to Afghanistan in 1968, where the High Council of Jamiat-e Islami gave him the duty of organizing the university students.

Sayed Noorullah Emad, who was then a young Muslim in the University of Kabul, became the General Secretary of the party and, later, its deputy chief.

Rabbani alongside Ahmad Shah Massoud and others planned to take action either against the Daoud government or people who they deemed communist in 1975, but failed.

For that purpose we prepared a list of eighty military and civilian communists and instructed our companions to carry it out.…Surprisingly news of the failure of the uprising in Laghman and other regions reached us in Peshawar.

[8] When the Soviets intervened in 1979, Rabbani helped lead Jamiat-e Islami in resistance to the People's Democratic Party of Afghanistan regime.

[15] In 2011, just days before he died, Rabbani was trying to persuade Islamic scholars to issue a religious edict denouncing suicide bombings.