Kayqubad I (1188-1237,) is the Seljuq Sultan of Rûm who reigns from 1220 to 1237.

He expands the borders of the sultanate at the expense of his neighbors, particularly the Mengujek emirate and the Ayyubids, and establishes a Seljuq presence on the Mediterranean with his acquisition of the port of Kalon Oros, later renamed Ala'iyya in his honor.

He also brings the southern Crimea under Turkish control for a brief period as a result of a raid against the Black Sea port of Sudak.

The sultan, sometimes styled "Kayqubad the Great", is remembered today for his rich architectural legacy and the brilliant court culture that flourishes under his reign.

Kayqubad's reign representsthe apogee of Seljuq power and influence in Anatolia, and Kayqubad himself is considered the most illustrious prince of the dynasty.

In the period following the mid-13th century Mongol invasion, inhabitants of Anatolia frequently look back on his reign as a golden age, while the new rulers of the Anatolian beyliks seek to justify their own authority through pedigrees traced to him.