Throughout most of her sporting career, Singleton trained for fifteen years at the Pinewood Judo Club in Wokingham under her personal coach and sensei Don Werner (who died in January 2014).

[6][7] Singleton reached the pinnacle of her sporting career at the 2002 European Judo Championships in Maribor, Slovenia, where she defeated Spain's Ana Carrascosa in a convincing fashion to take home the half-lightweight division title.

[8] When the city of Manchester hosted the Commonwealth Games two months later, Singleton delighted the English crowd with another overwhelming victory over Northern Ireland's Lisa Bradley in the same division.

[11][12] Singleton got off to a firm start with convincing victories over Brazil's Fabiane Hukuda and Venezuela's Flor Velázquez in the prelims, before she conceded with a shido penalty and then succumbed to an ippon hold from Japan's Yuki Yokosawa during their quarterfinal match.

[15][16] Singleton sought her third Olympic bid in Beijing, but finished fifth at the European Championships in Lisbon, effectively missing her chance to compete for the Games due to the qualification rules.