She was one of the daughters born to the Seleucid Monarchs Antiochus II Theos and Laodice I.
[1] Among her brothers was the Seleucid King Seleucus II Callinicus and prince Antiochus Hierax.
In c. 257 BC, Antiochus II Theos arranged for Stratonice to marry Ariarathes III.
[2] Between 255 BC-250 BC, Antiochus II Theos recognized the Seleucid client state of Cappadocia to become an independent kingdom.
In 255 BC, Ariarathes III of Cappadocia started co-ruling with his father, Ariamnes II.