She studied drama at the University of Manchester, before embarking on a career in children's theatre. In 1987 she was cast as Ace in Doctor Who.
Aldred's Doctor Who tenure spanned the last nine stories of the show's run. The Ace character was a troubled teenager from West London. The Doctor found her serving milkshakes on an ice-covered planet in the episode Dragonfire. She joined the Doctor on his travels and appeared in several stories (Ghost Light, The Curse of Fenric, and Survival) that explored her character to an extent that previous companion characters had not been.
Both before and since Doctor Who, Aldred has had a varied and busy television career, particularly in children's programming, where she has presented educational programmes such as Corners, Melvin and Maureen's Music-a-grams and the long running BBC series Words and Pictures. She has also performed on radio and in the theater.
Sophie Aldred married Vince Henderson on July 12 1997. They have a son.