The Codex de Roda names "Ordonii regis" as the son of "domni Ranimiri regis, frater Adefonsi regis et Froila" and "alia uxore Galliciensis". The Crónica de Sampiro (interpolated, España Sagrada edition) records that “Ranimirus…Rex” and “Tarasia Regina cognomento Florentina” had “Ordonium, Sanctium et Geloiram”. The date of King Ordoño´s marriage suggests that he was born from his father´s first marriage and provides the basis for estimating his birth to . "Ranimirus…princeps" confirmed the possessions of Santiago de Compostela by charter dated 18 Nov 932, subscribed by "Veremudus regis filius, Hordonius regis filius…". "Ranimirus rex Hordonii quondam…principis proles…cum…domino Urraca regina" confirmed the privileges of Santiago de Compostela by charter dated 21 Feb 934, subscribed by "Ordonius filius regis, Garsea frater regis…". “Vrrache regina, Veremudus prolis regis, Ordonius prolis regis...” confirmed the charter dated 25 Jun 934 under which King Ramiro II donated "locum...Apeliare super ripam...Torio" to the monastery of San Cosme and San Damián. “Ranimirus…rex” donated property to Celanova by charter dated 11 Aug 941, confirmed by “Hurraca regina, Hordonius prolis regis, Santius prolis regis”. "Ranimirus rex" donated property to Sahagún by charter dated 29 Mar 945, subscribed by "Veremudus rex proles Adefonsi principis, Ordonius proles regis, Sancius frater Ordonius proles regis, Osorio Munniz, Assur Fernandiz, Aurelius Baroncelli". “Ranimirus rex et Urracha regina et prolis eius Ordonius regis” donated "villa...Perales et Volpiare et Villa Rezmiro secundum obtinuit illas Gundisalbo Moniz" to Vega by charter dated 24 Sep 946, confirmed by “...Sanzius filius regis, Gelvira prolis regis et Deo vota...”. “Hordonius prolis regis, Sancius prolis regis, Rudericus Uelasquiz, Hordonius prolis domni Adefonsi regis” confirmed the charter dated 13 Jun 950 under which Bishop Rosendo agreed territorial boundaries with the inhabitants of Villaza.
The Crónica de Sampiro, as reproduced in the Historia Silense, records that "filius eius Ordonius" succeeded King Ramiro II in "era DCCCCLXXXVIII". He succeeded his father in 951 as ORDOÑO III King of León. His succession was challenged by his brother Sancho. Caliph Abd al-Rahman's troops launched further raids against Galicia and Castile between 953 and 955, but were defeated by Fernán González Conde de Castilla near San Esteban de Gormaz in 955. In 955, King Ordoño sacked Lisbon and was able to impose an advantageous peace on the caliph.
The Crónica de Sampiro, as reproduced in the Historia Silense, records the death of King Ordoño in "urbe Zamora" and his burial "iuxta aulam sancti Salvatoris iuxta sarchofagum patris sui Ramiri regis". The Chronicon Regum Legionensium names "King Ordoño…and King Sancho" as the sons of "King Ramiro", when reporting their reburial in light of the threatened invasion of the kingdom of León and Asturias by Al-Mansur, incorrectly naming his wife "Elvira". The Chronicon Compostellani records that “Ordonius” reigned five years and seven months. 1