Mohammad Ali Jafari (Persian: محمدعلی جعفری, born 1 September 1957, also known as Aziz Jafari and Ali Jafari) is an Iranian military officer who was the commander-in-chief of the Iranian Revolutionary Guard Corps (IRGC) from 2007 to 2019. He was appointed by Supreme Leader Ali Khamenei on 1 September 2007, succeeding Major General Yahya Rahim Safavi, and was replaced in 2019 by Hossein Salami.

According to a 2 September 2007 report by Radio Free Europe/Radio Liberty, Radio Farda, Jafari was close to the conservative subfaction, which included Mohsen Rezaee, the secretary of the Expediency Discernment Council and former commander of the IRGC and Mohammad Bagher Ghalibaf, a former IRGC member and the mayor of Tehran. The replacement of Safavi was thought to be a move to strengthen the conservative faction as a counterweight to the radicalizers around President Mahmoud Ahmadinejad, to whom Safavi was close.

Jafari was seen as a tactician, organizer, and 'technical' military man, according to Radio Free Europe. The EU's official journal said the three Iranian Revolutionary Guard members, Jafari, General Qasem Soleimani, and the Guard's deputy commander for intelligence, Hossein Taeb, were subject to sanctions for providing equipment and support to help the Syrian regime suppress Syrian protesters.

Jafari was born in Yazd and completed his primary and secondary education there. In 1977 he was admitted to Tehran University, where he studied civil (construction) technology. As a student, he participated in anti-Shah protests in Tehran, and was arrested and sent to jail for this. He represented his university department in the Islamic Organization of Tehran University.

At the start of the Iran–Iraq War Jafari fought with the Basij paramilitary force. In 1981, he became a part of the Revolutionary Guards where he rose to serve as a commander of operative battlefields of south and west during the early 1980s. He also participated as an assistant^{[clarification needed]} in the operation of Susangerd, and served as commander of the Ashura Brigade, as well as of the Headquarters of Qods and Najaf.

After the war Jafari returned to university to complete his education, and in 1992 received a degree in civil (construction) technology. In 1992 and 1993, he taught at the War University of the Revolutionary Guards. He was appointed to head "a strategic research center to map out new defensive and military strategies in response to what Iran's leadership has seen as evolving threats in the Middle East", according to Radio Free Europe/Radio Liberty. Jafari is said to have formed many of his ideas on unconventional or asymmetric warfare at the research center.

Prior to his appointment as leader of the guards, he was also the commander of Thar-Allah Headquarters in Tehran. In 1999, according to Radio Farda, Jafari was among 24 IRGC commanders who signed a letter to President Mohammad Khatami, warning him that his liberalizing policies, at a time of civil unrest in Tehran, threatened the country's leadership.

Jafari is a brother-in-law of Mohammad Bagher Zolghadr, a former deputy interior minister.