On 1 March 649 a mayor of the palace of Clovis II yielded his lordship over a royal desmesne in the Forest of Brotonne on the banks of the Fontenelle, a tributary of the Seine, to two monks, Wandrille and Gond.

Wandrille was a man of great humility and gentleness. He was also characterized by a remarkable obedience towards the bishop of Rouen, Saint Ouen, who had desired the foundation of the monastery. Wandrille built seven churches in the valley of the Fontenelle, dedicating them to Saint Peter, Saint Paul, Saint Lawrence, Saint Pancras, Saint Saturninus, Saint Amand and the Blessed Virgin Mary. Until his death on 22 July 668 he governed a flourishing abbey.

His successors, among whom were Saint Lantbert (+688), later bishop of Lyons, and Saint Ansbert (+695), later bishop of Rouen, presided over an increase in both the size and the merit of the community. Fontenelle, along with its dependent foundations, became a nursery of saints, counting among its members Saint Erembert (+671), Saint Condedus (+680), Saint Wulfram (+c.697), Saint Bain (+710), Saint Hildebert (+701), Saint Sindard, Saint Desiderius, Saint Hermeland (+720), Saint Bagga, Saint Benignus (+724), Saint Milon (+730), Saint Hugues (+c.732), Saint Landon (+735), Saint Ermier (+740), Saint Ravenger (+750), Saint Austrulf (+753), Saint Wandon (+754), Blessed Hardouin (+812), and Saint Hartbain.

This time of prosperity lasted until about 740, when a series of lay abbots began to despoil both temporal and spiritual goods. In 823 Saint Ansegisius succeeded Einhard as abbot. He had already reformed various monasteries, including Luxeuil. At Fontenelle he renewed his sons' fervour, and fostered intellectual achievements as well as the spiritual life, while reinstating the observance of the Rule, rebuilding, and enriching the library and the treasury.

The Gesta Abbatum, written between about 820 and 830, recounts in the style of the Roman Liber Pontificalis the lives and deeds of all the abbots from Wandrille to Ansegisius. It is said to be the most ancient monastic chronicle of the Western Church. It mentions the existence of a bouleuterion or meeting-hall; this is the oldest surviving testimony of a chapter house.

At about the same time as the composition of the Gesta, the seventh century Vita Wandregisili was rewritten, as were the lives of Saint Ansbert and Saint Wulfram. This period also saw the composition of the lives of Saint Ansbert, Saint Condedus, and Saint Hermeland. But the Vikings put an end to this time of renewed prosperity, first extracting tribute, and then sacking and burning the monastery on 9 January 852. The monks fled with the relics of Saint Wandrille and Saint Ansbert. After lengthly wanderings in northern France, the monks and their relics found a home in Ghent in 944.