She functioned as regent of Normandy during the absence of her spouse, as well as the adviser to him and later to his successor, their son Richard II.

The names of Gunnor's parents are unknown, but Robert of Torigni wrote that her father was a forester from the Pays de Caux and according to Dudo of Saint-Quentin she was of noble Danish ancestry.

But when Richard was prevented from nominating their son Robert to be Archbishop of Rouen, the two were married, "according to the Christian custom", making their children legitimate in the eyes of the church.

[14] In one of her own charters after Richard's death she gave two alods to the abbey of Mont Saint-Michel, namely Britavilla and Domjean, given to her by her husband in dower, which she gave for the soul of her husband, and the weal of her own soul and that of her sons "count Richard, archbishop Robert, and others..."[15] She also attested a charter, c. 1024–26, to that same abbey by her son, Richard II, shown as Gonnor matris comitis (mother of the count).

[16] Gunnor, both as wife and countess,[e] was able to use her influence to see her kin favored, and several of the most prominent Anglo-Norman families on both sides of the English Channel are descended from her, her sisters and nieces.