Kaykhusraw I (Old Anatolian Turkish: كَیخُسرو or Ghiyāth ad-Dīn Kaykhusraw bin Qilij Arslān; Persian: غياث الدين كيخسرو بن قلج ارسلان), the eleventh and youngest son of Kilij Arslan II, was Seljuk Sultan of Rûm. He succeeded his father in 1192, but had to fight his brothers for control of the Sultanate, losing to his brother Suleiman II in 1196. He ruled it 1192-1196 and 1205-1211.
He married a daughter of Manuel Maurozomes, son of Theodore Maurozomes and of an illegitimate daughter of the Byzantine emperor Manuel I Komnenos. Manuel Maurozomes fought on behalf of Kaykhusraw in 1205 and 1206.
In 1207 he seized Antalya from its Frankish garrison and furnished the Seljuq state with a port on the Mediterranean.
According to Niketas Choniates, he was killed in single combat by Theodore I Laskaris, the emperor of Nicaea, during the Battle of Antioch on the Meander.
His son by Manuel Maurozomes' daughter, Kayqubad I, ruled the Sultanate from 1220 to 1237, and his grandson, Kaykhusraw II, ruled from 1237 to 1246.