Constantine was born at
Constantinople, an illegitimate son born before an uncanonical fourth marriage. To help legitimize him, his mother gave birth to him in the Purple Room of the imperial palace, hence his nickname Porphyrogennetos. He was symbolically elevated to the throne as a two-year-old child by his father and uncle on May 15, 908.
In June 913, as his uncle
Alexander lay dying, he appointed a seven-man
regency council for Constantine. It was headed by the Patriarch
Nicholas I Mystikos, the two
John Eladas and
John Lazanes, the otherwise obscure Euthymius and Alexander's henchmen Basilitzes and Gabrielopoulos. Following Alexander's death, the new and shaky regime survived the attempted usurpation of
Constantine Doukas, and Patriarch Nicholas Mystikos quickly assumed a dominant position among the regents.
Constantine and Simeon dining
Patriarch Nicholas was presently forced to make peace with
Tsar Simeon of
Bulgaria, whom he reluctantly recognized as Bulgarian emperor. Because of this unpopular concession, Patriarch Nicholas was driven out of the regency by Constantine's mother
Zoe. She was no more successful with the Bulgarians, who defeated her main supporter, the general
Leo Phokas, in 917. In 919 she was replaced as regent by the
Romanos Lekapenos, who married his daughter
Helena Lekapene to Constantine. Romanos used his position to advance to the ranks of
basileopatōr in May 919, to kaisar (
Caesar) in September 920, and finally to co-emperor in December 920. Thus, just short of reaching nominal
majority, Constantine was eclipsed by a senior emperor.
Constantine's youth had been a sad one due to his unpleasant appearance, his taciturn nature, and his relegation to the third level of succession, behind
Christopher Lekapenos, the eldest son of Romanos I Lekapenos. Nevertheless, he was a very intelligent young man with a large range of interests, and he dedicated those years to studying the court's ceremonial.
Romanos kept and maintained power until 944, when he was deposed by his sons, the co-emperors
Constantine. Romanos spent the last years of his life in exile on the Island of
Prote as a monk and died on June 15, 948.
 With the help of his wife, Constantine VII succeeded in removing his brothers-in-law, and on January 27, 945, Constantine VII became sole emperor at the age of 39, after a life spent in the shadow. Several months later, Constantine VII crowned his own son
Romanos II co-emperor. Having never exercised executive authority, Constantine remained primarily devoted to his scholarly pursuits and relegated his authority to bureaucrats and generals, as well as to his energetic wife Helena Lekapene.
In 949 Constantine launched a new fleet of 100 ships (20
dromons, 64 chelandia, and 10 galleys) against the
Arab corsairs hiding in
Crete, but like his father's attempt to retake the island in 911, this attempt also failed. On the Eastern frontier things went better, even if with alternate success. In 949 the Byzantines conquered
Germanicea, repeatedly defeated the enemy armies, and in 952 they crossed the upper
Euphrates. But in 953 the
Sayf al-Daula retook Germanicea and entered the imperial territory. The land in the east was eventually recovered by
Nikephoros Phokas, who conquered
Hadath, in northern
Syria, in 958, and by the general
John Tzimiskes, who one year later captured
Samosata, in northern
Mesopotamia. An Arab fleet was also destroyed by
Greek fire in 957. Constantine's efforts to retake themes lost to the Arabs were the first such efforts to have any real success.
Constantine had active diplomatic relationships with foreign courts, including those of the
Abd ar-Rahman III and of
Otto I, Holy Roman Emperor. In the autumn of 957 Constantine was visited by
Olga of Kiev, regent of the
Kievan Rus'. The reasons for this voyage have never been clarified; but she was baptised a Christian with the name Helena, and sought Christian missionaries to encourage her people to adopt
Christianity. According to legends, Constantine VII fell in love with Olga, however she found the way to refuse him by tricking him to become her
godfather. When she was baptized, she said it was inappropriate for a godfather to marry his
Constantine VII died at Constantinople in November 959 and was succeeded by his son
Romanos II. It was rumored that Constantine had been poisoned by his son or his daughter-in-law