Bonnie Langford attended The Arts Educational School and the Italia Conti Academy stage school. She first came to public attention when, aged 6, she won the talent show Opportunity Knocks. This led to early fame in the television series Just William, the 1976 film Bugsy Malone and the 1977 film Wombling Free. At this time, she was associated with fellow child star Lena Zavaroni. Langford received a fair amount of criticism in her early career, as she had been widely perceived as overly precocious.

Between 1986 and 1987 Langford played the role of Mel, companion to both the Sixth and Seventh Doctors in the classic science fiction series Doctor Who. Langford was a featured dancer in BBC One's popular light entertainment series The Hot Shoe Show which she co-presented with Wayne Sleep. Langford is a panto regular. In 2004–05 she played the title role in Dick Whittington and the following season she played Prince Charming in Cinderella.

Bonnie was thrilled to take part in ITV1's hit Saturday night show Dancing on Ice for which she undertook one of the most chilling challenges in her career. Partnered by US Pairs figure skating champion Matt Evers and coached by the World famous Olympic Ice Dance champions Jayne Torvill and Christopher Dean, Bonnie skated her way into the final with spectacular, daring and beautiful routines. Having never in her life skated before, it was an incredible achievement. Subsequently, she returned to the West End stage to play Roxie Hart in the Global phenomenon that is Chicago at both the Adelphi and Cambridge Theatres.

On London's West End stage, she has starred in a further seven smash hit musicals including Gone With The Wind at the Theatre Royal, Drury Lane; Gypsy - Piccadilly Theatre; Cats - New London Theatre (original London cast); The Pirates Of Penzance first at the Theatre Royal, Drury Lane and later at the London Palladium; Peter Pan - The Musical (playing the title role) at the Aldwych Theatre; Me And My Girl - Adelphi Theatre, and her much acclaimed portrayal of Charity in Sweet Charity at the Victoria Palace Theatre. She has also appeared in three Royal Variety Performances and numerous Royal Galas.

She has also made a number of guest appearances on television, including Agatha Christie's Miss Marple on ITV (playing Betty Johnson in the episode By the pricking of my thumbs, February 2006), The Catherine TateShow (late 2006), Supermarket Sweep (February 2007) and the children's programme Hider In The House (March 2007).

Langford has supported the BBC's Children in Need appeal (1993) and Comic Relief appeal (2007). For the latter she appeared in the video for the charity single I'm Gonna Be (500 Miles) by The Proclaimers, Peter Kay and Matt Lucas.

She has also appeared in celebrity versions of game shows to support Childline when she played in Who Wants to Be a Millionaire? in December 2006, and the CdLs Foundation on both The Weakest Link in January 2007(which she won) and Who Wants to Be a Millionaire? in January 2008.

Langford lives with her husband, fellow actor Paul Grunert (most notable for appearances in ChuckleVision) whom she married in Mauritius in 1995, his daughter from a previous marriage, and their daughter born in 2000.