In 1722, he was confirmed by the shah as King of Kakheti following the death of Constantine's brother David II (Imām Qulī Khān).

He frequently feuded with his western neighbor and kinsman, Vakhtang VI of Kartli, who was declared by the Persian government deposed in 1723.

However, Vakhtang VI managed to bribe Ibrahim-Pasha who installed Prince Bakar as governor of Kartli and arrested Constantine.

In 1725, he succeeded in reestablishing himself in Kakheti and made peace with the Ottomans who recognized him as king in exchange of his conversion to Sunni Islam and paying an annual tribute.

Early in the 1730s, as Nader Khan Afshar pushed his quest to revive the Persian empire, Constantine made a fatal attempt to break with the Turks.