Constantine was the third son of Emperor Michael VIII Palaiologos (r. 1259–1282) and Theodora Doukaina Vatatzaina. He was born in autumn 1261 in Constantinople, which had just been recovered from the Latin Empire in August. He was hence a true porphyrogennetos ("purple-born") prince, and was often referred to as such. His father reportedly accorded him honours above even those of a despotes. From his marriage to Irene Palaiologina Raoulaina, he had one son, the panhypersebastos John Palaiologos.