Having won four titles at the 1950 British Empire Games, Jackson came as a favourite to the Helsinki 1952 Summer Olympics. She won both the 100 m, in a then-world-record-equalling time of 11.5, and the 200 m, winning the first Olympic athletics track titles for Australia since Edwin Flack in 1896. Having more strong runners in the team (consisting of Shirley Strickland, Winsome Crisps and Verna Johnston in addition to Jackson), the Australian 4 × 100 m relay team was also a favourite for the gold, but a faulty exchange meant Jackson's chances for third gold medal were gone. The Americans, anchored by Catherine Hardy (later Lavender), won in an upset, setting a new world record time of 45.9 seconds. Later in 1952, Jackson lowered the 100 m world record time to 11.4, running this new record in a meet at Gifu, Japan on 4 October 1952.