The Chronicle of Alberic de Trois-Fontaines names "comes Renaldus [de Burgundia] fratrem comitem Guilelmum" when recording his marriage.
He succeeded in 1120 as Comte de Mâcon. Comte d'Auxonne 1127. He joined the Second Crusade 1147-1149. Guillaume enjoyed some influence in Vienne as shown by the following document: Konrad III King of Germany confirmed the rights of the archbishop and chapter over Vienne, specifying that he removed (“alienamus”) “Willelmum Matisconensem comitem” [Guillaume [III] Comte de Mâcon] from “predicta urbe”, by charter dated 6 Jan 1146. “Raynaldus Burgundiæ comes” donated property to Besançon cathedral, with the consent of “fratris nostri Guillermi comitis et...collateralis nostræ Agathæ Lotharingiæ ducis filiæ”, by charter dated 1148.
Regent of Bourgogne-Comté for his niece Beatrix, whom he attempted to deprive of her inheritance: one of Sigebert’s continuators records, when recording Beatrix’s marriage, that “filiam comitis Burgundionum Reinaldi” had been imprisoned by “patruus suus comes Wilhelmus” after her father died. “Comes Stephanus...et fratrem meum comitem Gerardum” settled disputes with Charlieu abbey, with the consent of “matris nostræ...comitis Willelmi patris nostri et avi nostri domini Theobaldi de Treva”, by charter dated 28 Oct 1157. 1
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