Christopher was given the position of megas hetaireiarches (commander of the palace guard) in spring 919, after Romanos assumed guardianship of the underage Emperor Constantine VII.

Romanos, who had made himself emperor in 920, raised Christopher to co-emperor on 21 May 921 to give his family precedence over Constantine VII's Macedonian line.

Christopher was the eldest son and the second-oldest child (after his sister Helena) of the Byzantine military general Romanos Lekapenos and his wife Theodora.

Before his father had taken the throne, Christopher had married Sophia, the daughter of Niketas, a wealthy Slav from the Peloponnese who held the high court rank of patrikios.

[4][7][18] On the third day of the feast, 10 October, held in Pegae, at the insistence of the Bulgarians, perhaps engineered by Romanos, Christopher was advanced before Constantine Porphyrogennetos, making him first among the rather large group of co-emperors.

[3][7][19] The motive behind the attempted coup was perhaps Christopher's poor health, and fears by his wife and her father that, should he die prematurely, they would lose their status.

As Romanos' favourite son, he was much mourned by his father, who shed tears "more than the Egyptians" according to Theophanes Continuatus, and thereafter increasingly became devoted to religious pursuits.