She claimed the 400 m titles at the 2010 Central American and Caribbean Junior Championships and 2010 CARIFTA Games, as well as four medals with the Bahamas in the 4 × 100 metres relay and 4 × 400 metres relay. Sixteen-year-old Miller-Uibo became the first Bahamian to be 400 m champion at the 2010 World Junior Championships in Athletics and the youngest woman to ever win the event. She won the gold medal in a time of 52.52 denying Margaret Etim who finished second in 53.05 (this was the slowest winning time in the history of the event).