Member of Wolverhampton & Bilston Athletic Club coached initially in the progressive days by John Moogan, and, subsequently by National Track and Field Coach Wilf Paish. Sanderson was the UK's leading javelin thrower from the mid-1970s, winning silver in the 1978 European championships and gold in the Commonwealth Games three times (1978, 1986, 1990), but was eclipsed during the 1980s by the up-and-coming Fatima Whitbread, with whom she shared a long-standing rivalry.
When Sanderson won the gold medal at the 1984 Summer Olympics in the javelin, becoming the first British woman ever to win Olympic gold in this event, her victory was quite unexpected. In the end, her career outlasted Whitbread's, and she competed at senior international level until 1996.
Her best performance in the javelin was 73.58 m (241 ft 4 3⁄4 in) set in Edinburgh on 26 March 1983.
Sanderson was appointed a Member of the Order of the British Empire (MBE) in the 1985 New Year's Honours, following her Olympic gold, raised to Officer (OBE) in the 1998 New Year's Honours for her charity work, and to Commander (CBE) in the 2004 New Year's Honours for her services to Sport England.
In 2004 Sanderson was awarded a Sunday Times Lifetime Achievement Award.
There is a housing estate named after her in her adopted home town of Wednesfield: Sanderson Park. It is located in the vicinity of the playing fields of her former school, Wards Bridge High School.