Born in St. Ann, Jamaica, West Indies Federation, Jackson reached the 100m and 200m finals in the 1984 Los Angeles Olympics, finishing fifth in both.

She won a bronze medal in the 200m at the 1987 IAAF World Indoor Championships behind Heike Drechsler and Merlene Ottey.

The highlight of her career was at the 1988 Seoul Olympics, where she won a silver medal in the 200m behind Florence Griffith-Joyner's still-standing world record of 21.34.

In the process, she finished ahead of then-200m World Champion Silke Moller (5th), Heike Drechsler (3rd) and teammate Merlene Ottey (4th).

Jackson concluded her international career by finishing sixth in the 200m final at the 1992 Barcelona Olympics.