He suppressed an uprising of the Basques, from whom he took Munia (Munina), of noble family, and later married. She later gave birth to Alfonso (afterward Alfonso II the Chaste) and Jimena, mother of the hero of romance Bernardo del Carpio.
During his reign, the city of Oviedo was founded, on November 25, 761, when Abbot Máximo and his uncle Fromestano erected a church in honour of Saint Vincent there, and the good relations between the church and the kings of Asturias continued.
Fruela did not finish his reign happily. Having assassinated his brother Vimarano and with the nobles restless, he named as his successor Bermudo (son of Vimerano). Unfortunately a plot was formed against him, which ended with Fruela being assassinated in Cangas de Onis and his cousin Aurelio being raised to the throne instead.
The bodies of Fruela and his wife Munia are interred in the cathedral at Oviedo.