Constantine's parents are not mentioned in any primary sources,[2] but some scholars theorize that he was the son of Andronikos Doukas, a nobleman who served as strategos of Preslav during the reign of Basil II (r. 976–1025).

[6][2] He was an academic, addicted to endless debates about philosophy and theology, and he gained influence after he married, as his second wife, Eudokia Makrembolitissa, a niece of Patriarch Michael Keroularios.

[7] Severely undercutting the training and financial support for the armed forces, Constantine X disbanded the Armenian local militia of 50,000 men at a crucial point of time, coinciding with the westward advance of the Seljuk Turks and their Turcoman allies.

[11] His decisions to replace standing soldiers with mercenaries[12] and leaving the frontier fortifications unrepaired led Constantine to become naturally unpopular with the supporters of Isaac within the military aristocracy, who attempted to assassinate him in 1061.

He also suffered invasions by Alp Arslan in Asia Minor in 1064, resulting in the loss of the Armenian capital,[13] and by the Oghuz Turks in the Balkans in 1065,[14] while Belgrade was lost to the Hungarians.