A son of Emperor John V Palaiologos, Theodore was the first member of the Palaiologos dynasty appointed as the Despot of the Morea, following the final defeat of the rival Kantakouzenos clan, who under John VI Kantakouzenos had attempted to usurp rule of the Byzantine Empire.

Theodore conducted several military campaigns to expand his province, successfully annexing several Latin possessions that remained there since the aftermath of the Fourth Crusade.

Theodore was the youngest surviving son of the Byzantine Emperor John V Palaiologos and his wife Helena Kantakouzene.

Soon after the restoration of John V, Manuel was appointed to rule in Thessalonica, and Theodore was eventually transferred to Morea.

The Navarrese, under the leadership of Pedro de San Superano, seized control over Achaia following the death of James and launched attacks into Byzantine territories.

[4] Theodore bought Corinth between September 1395 and January 1396, but sold it to the Knights Hospitaller in 1397 as he was unable to rebuild its fortifications and properly defend it.