The 16-year-old Beaulieu Convent student claimed her third British title after finishing in first place in both the FITA and Hereford round shoots on Saturday and Sunday respectively at Lilleshall in Shropshire.
O’Sullivan, who finished third in the Junior World Championships in Mexico last year, won the FITA round with a score of 1,293.
The Archers of Jersey markswomen’s nearest rival scored 1,191.
In the Hereford shoot, O’Sullivan totalled 1,212 which was 36 points clear of the second-placed competitor.
O’Sullivan is now the holder of three British titles, indoor and outdoor at junior level and indoor at senior level.
The Jersey archer is supported by Education, Sport and Culture and Condor.
