Its reconquest by Christian powers began in 798; in that year Louis of Aquitaine ordered a Goth Borrell to enter the abandoned region and repair the castles of Vic, Cardona, and Casserès.

After the successful siege of Barcelona in 801, Borrell, already Count of Cerdanya and Urgell, received Osona as a countship from his liege lord, King Louis.

After the rebellion of 826, during which Guillemó and Aissó succeeded in taking it with help from the Emirate of Córdoba, Osona remained depopulated and outside of Frankish control until 879.

In 879, Wilfred the Hairy began the repopulation of the county with free minores, who cultivated the lands given them as aprisiones; they turned Osona into a central and important part of Catalonia.

After that, it was reattached to Barcelona, but was augmented by the addition of the County of Manresa, which was subsumed within Osona and ceased to be a distinct polity in the region.