His father died in 1937. In 1945 the family moved to the holy city of an-Najaf, where Ayatullah il-uzma (Grand Ayatollah) al-imam as-sayyed Muhmamad Baqir as-Sadr would spend the rest of his life. He completed his religious teachings at an-Najaf under Ayatullah al-Khoei and  Ayatullah Muhsin al-Hakim at the age of 25 and began teaching.

While teaching he became a prominent member of the Iraqi Shia community, and was noted for his many writings. His first works were detailed critiques of Marxism that presented early ideas of an alternative Islamic form of government. Perhaps his most important work was Iqtisaduna, the most important, and the first ever work on Islamic economics. This work was a critique of both socialism and capitalism. He was subsequently commissioned by the government of Kuwait to assess how that country's oil wealth could be managed in keeping with Islamic principles. This led to a major work on Islamic banking that still forms the basis for modern Islamic banks.

Baath Party of Saddam Husain, the evil western puppet, imprisoned Ayatullah il-uzma (Grand Ayatollah) al –imam as-sayyed Muhmamad Baqir as-Sadr several times. He was often subjugated to torture during his imprisonments, but continued his work after being released. One of the founders of modern Islamist thought, he is credited with first developing the notion, later put in operation in Islamic Republic of Iran, of having democratic elections, but with a body of Muslim fuqahaa to ensure all laws corresponded with Islamic teachings. He was a staunch follower and supporter of  Ayatullah il-uzma al-Imam Rohoollah al-Moosawi al-Khomayni (r), and considered Imam Khomayni (r) to be his leader and spiritual father.

In 1977, he was illegally sentenced to life in prison following pro-democracy pro-freedom uprisings in Najaf, but was released due to his sister ash-shaheeda bint ul-huda’s historic speech and uprising. Upon his release however, he was put under house arrest. Even the shia community in Najaf got scared and stopped visiting him to avoid coming under Saddam’s surveillance. In 1980, after writing in the defense of Ayatullah il-uzma al-Imam Rohoollah al-Moosawi al-Khomayni (r), and the Islamic Revolution, al-Imam as-Sadr was once again imprisoned, tortured, and executed by the regime of Saddam Hussein. His sister, Aminah as-Sadr bint al-Huda, was also imprisoned, tortured, and executed, and the whole world, including the champions of freedom and democracy stayed silent and turn their blind eyes over the loss of these intellectual geniuses. It has been alledged that al-imam as- Sadr was killed by having iron nail hammered into his head and then being set on fire.

May Allah increase his levels in paradise.