While still a youth, he was sent by his father as a hostage with his entourage to Nogai Khan of the Golden Horde, to maintain the peace between the Serbs and Tatars.

In 1320, Dečanski was permitted to return to Serbia and was given the appanage of Budimlje,[10] while his half-brother Stefan Konstantin, held Zeta.

[10] Konstantin was crowned King in Zeta, but civil war broke out immediately as both Dečanski and his cousin, Stefan Vladislav II, claimed the throne.

[12] Dečanski revealed that his eyesight was still intact, claiming a miracle, and the populace rallied behind him believing the restoration of his sight to be a sign from God.

[13] In the meantime, Vladislav II had been released from prison upon Milutin's death and recovered the throne of Syrmia, which his father had established in northern Serbia.

[13] Also supported by Hungarians, Bulgarians, and Bosnians, Vladislav consolidated control over Syrmia and prepared for battle with Dečanski.

[13] Some of Vladislav's supporters from Rudnik, led by Ragusan merchant Menčet, took refuge in the nearby Ostrovica fortress, where they resisted Dečanski's troops.

[20] Michael Asen III divorced Dečanski's sister Anna and married the Byzantine princess Theodora Palaiologina instead.

In the most significant event of Dečanski's reign, he defeated and killed Michael Asen III in the Battle of Velbazhd (1330).

[24] On 21 August 1331 Dušan captured Petrič after a siege and imprisoned his father in Zvečan Fortress, where he died on 11 November 1331.