Before ascending the throne replacing George Terter I in 1292, Smilec had married an unnamed Byzantine princess, the daughter of the "sebastokratōr" Constantine Palaiologos, a half-brother of Emperor Michael VIII Palaiologos. Apart from the information that Smilec became emperor of Bulgaria according to the wishes of Nogai Khan, we know nothing of the circumstances of Smilec's accession. He was crowned by Patriarch Joachim III. Joachim III was executed for treason in 1300 by emperor Theodore Svetoslav, George Terter I's son, and historian John Van Antwerp Fine Jr. theorizes that the alleged treachery might be linked to the obscure period when Smilets overthrew George Terter I.