Seyyed Mojtaba Hosseini was born on August 5, 1977, in Qaemshahr, Mazandaran Province. After completing high school, he pursued a degree in nursing at a university in Babol. Upon earning his academic qualifications, he joined the Sarī branch of the Islamic Revolutionary Guard Corps (IRGC) to fulfill his military service.
Following his military service, he got married and was blessed with a daughter named Seyyedeh Fatemeh. A year later, he joined the Police Force in Tehran. After three and a half years, he transferred to Mazandaran Province, and on July 22, 2008, he was deployed to southeastern Iran.
On the morning of Monday, December 29, 2008, coinciding with the first day of Muharram, Seyyed Mojtaba was stationed at the gate of the military base, safeguarding the premises during a commemoration of the Ziyarat Ashura ritual. At that moment, a member of the Rigi Jundallah terrorist group attempted a suicide attack, driving a vehicle laden with several hundred kilograms of explosives into the base, aiming to target the security forces stationed there.
Upon witnessing the vehicle, Seyyed Mojtaba rushed to stop it and apprehend the driver. In an instant, a massive explosion shook the area, and Seyyed Mojtaba was assassinated in the line of duty.