Little is known of Majorian's beginnings, although he undoubtedly came from a high-standing family. His maternal grandfather had served Theodosius I as 'Master of Soldiers' and his father had been treasurer to Aetius. No doubt aided by such connections, Majorian made a military career and served as an officer to Aetius. But he was eventually dismissed by Aetius due to his wife's dislike of him.
He retired to his country house but was then recalled to high ranking military command by Valentinian III in AD 455, Aetius having died in AD 454.
After the assassination of Valentinian III in AD 455, Majorian did appear to be a likely candidate to succeed to the western throne, particularly as he enjoyed the support of Marcian, the emperor of the east.
Then in early AD 457 Marcian died. It was either Marcian in his last days or his successor Leo within his first days in power who elevated Majorian to the rank of patrician (patricius), who had by then become 'Master of Soldiers' for Gaul and was at the time campaigning against the Marcomanni.
Leo, most likely on the advice of the powerful western military figure Ricimer, then nominated Majorian as western emperor.
His first problem as emperor arose in Gaul, where there was considerable resistance against him, after Avitus, whom the people of Gaul had seen as one of their own, had been deposed.
Majorian is said to have been a very impressive character. Historians appear to lose any restraint in their praise for Majorian. One hence can conclude that he must have been a outstanding person.
First a Vandal raiding force was driven out of Campania in Italy, then Majorian began to assemble a massive invasion force with which to invade north Africa and which, in AD 460 he marched the army impressive army to Carthago Nova (Cartagena) in Spain.
With his fleet smashed, there was no way for Majorian to set his troops across to north Africa, and he was forced to come to terms with Geiseric, recognizing him as king of Mauretania and Tripolitania.
Though Ricimer, still the all-powerful head of the military, saw Majorian's failure in dealing with Geiseric as a shameful stain on the emperor's honour. Ricimer sought not to be associated with failure. No longer understanding Majorian as a viable emperor he therefore simply sought to depose him.
On 2 August AD 461 a mutiny broke out in Dertona (Tortona) as the emperor passed trough it on his return journey back to Italy from Spain. Caught up in the mutiny, Majorian was forced by the soldiers to abdicate. It is very likely the mutiny was organized from afar by Ricimer. In any case, five days later it was reported that Majorian had died from illness. Though it clearly appears more likely that he was simply murdered.