Gredal was first elected to the Folketing in 1971 as a member of the Social Democrats, and served in that role until 1979. She served as a Minister of Social Affairs from 1971 to 1973 and again from 1975 to 1978. In that role, she primarily focused on unemployment reform. She also pushed for an Equal Opportunities Council for Denmark, and was the delegate for the United Nations World Conference on Women in 1975. Gredal was elected as a Member of the European Parliament in 1979, and served two terms. She was on the Political Affairs Committee, as well as the Committee on Budgets. She also spent the last two years of her second term on the Environmental Committee. After her term ended in 1989, Gredal worked for European Movement International, and was the director of the Mental Health Association until her death in 1995.