Lebanese security officials said he died in a military hospital in Beirut from kidney failure after going into a coma Friday, the BBC reported.
Majid had led the Abdullah Azzam Brigades, which was linked to al-Qaida, since 2012. The group had carried out attacks across the Middle East, including one on the Iranian embassy in Lebanon in November, in which 23 people, including the Iranian cultural attache, were killed.
DNA tests had confirmed Majid's identity Friday.
Lebanon's justice minister, Shakib Qortbawi, said before Majid's death was announced the accused terrorist would be tired for crimes against the country's national security, the (Lebanon) Daily Star reported.
Qortbawi said Majid had been previously tried in absentia and would be tried again now that he had been detained.
The Saudi ambassador to Lebanon had hinted Riyadh would seek Majid's extradition, but Qortbawi said he would have to be tried in Lebanon first.