Annum was one of many athletes through the defunct National Sports Festivals organised annually in Ghana. She benefited from the sponsorship of Ghanaian athletes by the United States. She competed in the 1964 Olympic Games but did not advance past the preliminary stages in the long jump, placing 28th with a best jump of 5.45 meters.
She won gold at the All Africa Games in long jump in 1965 and in the 100 m and 200 m in 1973. She was a silver medalist in the 1970 British Commonwealth Games in Edinburgh in the 100 and 200 m. In 1974 she won the bronze medal for the 200 m at the British Commonwealth Games in Christchurch, New Zealand.
She placed 6th and 7th in the 100 and 200 m respectively, at the 1972 Munich Olympic Games.
She was honored in 2010 for her achievements in sports by the Action Progressive Institute in Ghana.