He was a student of 'Allamah Tabataba'i and Imam Khomeini and was considered to be one of the most influential contemporary Iranian clerics in expounding upon Islamic teachings, in keeping with the need of the time. Prior to the Islamic Revolution, Motahhari's intellectual struggle against the Marxist movement in Iran played a stellar role in turning away the youth from its ideology. He was one of the founders of Husayniyya Irshad, a very important center for the propagation of Islamic teachings prior to the revolution. Elucidating Islamic beliefs and acting according to the need of the time were the characteristics of Motahhari's intellectual activities. Islamic concepts that were earlier dealt with in a complicated and difficult manner were presented by Motahhari in a simple and easy manner in his own personal style. 

Motahhari was born on 3rd February 1920 in Fariman in one of the cities of Khorasan. His father, Muhammad Hasan Motahhari, was a well-known cleric of the locality. He studied in the Islamic seminary of Mashhad from the age of thirteen and after four years of education there, entered the Islamic seminary of Qom. He attended Ayatollah Burujirdi's lessons for eight years and that of Ayatollah Khomeini's for twelve years.

He met with Hajj Mirza 'Ali Agha Shirazi during his travels to Isfahan. This acquaintance laid down the foundation for him to start his expansive research on Nahj al-Balagha and culminated in his writing the book Glimpses of Najh al-Balagha. He was acquainted with Ayatollah Tabataba'i and formally studied under his presence for three years, but his relationship with him continued until the end of his life.

Motahhari moved to Tehran and taught at Sepahsalar School (present day Shahid Motahari University) and Marvi School. He published his first work i.e. the book Principles of Philosophy and the Method of Realism. He commenced his teaching at Faculty of Theology and Islamic Studies, University of Tehran. In the course of these years, Motahhari had a close relationship with the group "Fada'iyan-i Islam" and used to give them his advice.

On 15th Khordad 1342/5th June 1963, after the arrest of Imam Khomeini over the peoples' objections on the Pahlavi reign, Motahhari was imprisoned along with other clerics and was released after 43 days. After the uprising of 15th Khordad, he started assisting Jam'iyyat Mu'talifa Islami.

One of important activities of Motahhari was building the Irshad religious center with the help of some friends in the year 1346/1386-1387. On the Day of Ashuraof 1390 A.H/18 March 1970 which corresponded to Isfand 1348, Motahhari gave a speech against Zionism which resulted in his arrest. In 1349/1970-71, he was arrested for inviting people to gather help for the homeless Palestinians and was subjected to investigation. In 1350/1971-72, he was arrested by SAVAK for working in association with the Irshad religious center. He withdrew himself from the Irshad center in the year 1349/1970-71 for certain reasons.

In the decade of the 1350s/1970s, on the advice of Imam Khomeini, he travelled to Qom for two days every week and taught at the Islamic seminary of Qom; simultaneously, in Tehran, he continued his educational gatherings and classes at home and other places. From 1351/1972-73 -1353/1974-75, Motahhari lectured at religious centers in Tehran until 1354/1975-76 when he was banned from lecturing.

In 1355/1976-77, the regime of the Shah retired Motahhari from Faculty of Theology and Islamic Studies, University of Tehran under the pretext of having a disagreement with a communist professor from the same university. In the same year, with the help of a few companions in Tehran, he founded the Association of the Resistant Clergy of Tehran (Jami'iyi Rawhaniyyat Mubariz-i Tehran). He also met with Imam Khomeini by journeying to Najaf.

In 1356/1977-78, Motahhari held an important role in commemorating the fortieth day of martyrdom of Mustafa Khomeini in the Mosque of Ark, Tehran. Imam Khomeini in a letter addressed to him, asked him to thank all those present in the Mosque of Ark. After the escalation of the Iranian peoples' struggle against the Pahlavi reign in the year 1357/1979 and after the regime's shifting of Imam Khomeini to Paris, Motahhari visited Paris and took over the responsibility of forming the Council of the Islamic Revolution from Imam Khomeini.

Morteza Motahhari was returning from a gathering at night on May 1, 1979 when he was assassinated by the terror group Furqan, and thus attained martyrdom.