Alexios I Komnenos was born into the powerful Komnenos family, one of the leading aristocratic clans of Byzantium. He rose to power during a time of deep political instability and external threats.

By the late 1070s, the Byzantine Empire was in deep crisis. After the catastrophic defeat at Manzikert (1071), the Seljuk Turks had overrun much of Asia Minor. At the same time, the Normans under Robert Guiscard were threatening the empire’s western borders. Emperor Nikephoros III Botaneiates (r. 1078–1081), an aging general, had little ability to manage these threats. His rule alienated both the military aristocracy and the populace.

The Komnenos family, one of the most powerful military dynasties, positioned itself as an alternative. Alexios, then a rising general in his early 30s, gained strong support from the army, especially in Thrace and Asia Minor, the influential Doukas family, into which he married (Irene Doukaina became his empress), and the Orthodox Church, led by Patriarch Kosmas I, who later crowned him.

On 1 April 1081, Alexios and his supporters marched on Constantinople. The city gates were opened by sympathizers inside, and Nikephoros III abdicated without significant resistance. On 4 April 1081, Alexios was formally crowned emperor in Constantinople’s Hagia Sophia, founding the Komnenian dynasty that would rule for over a century.