Foster was born in 1958 in Morrinsville, a provincial town in the Waikato region of New Zealand.
Foster first competed internationally at the 1978 World Rowing Championships at Lake Karapiro, New Zealand. With the women's coxed four and the women's eight, she won both B-finals. At the 1981 World Rowing Championships at Oberschleißheim, Germany, she came fifth in the women's single sculls. At the 1982 World Rowing Championships in Lucerne, Switzerland, she won a bronze medal in the single sculls.
She represented New Zealand in the single sculls event at the 1984 Olympics, coming seventh overall in the single sculls. At the 1986 World Rowing Championships at Nottingham in the United Kingdom, she won a Bronze in the women's double sculls with Robin Clarke. She was the flagbearer at the 1986 Commonwealth Games, and won golds in the Women's Single Sculls and in the Women's Double Sculls with Robin Clarke.
In the 1987 Queen's Birthday Honours, Foster was appointed a Member of the Order of the British Empire, for services to rowing.
