Sinclair became a glamour model when she was 16.Most of her modeling was glamour and softcore in British men's magazines such as Fiesta. For over two years in the mid-1990s, she was featured monthly in Club magazine. She was a popular Page 3 girl. Sinclair appeared in nine Playboy lingerie special editions, sometimes as "Charmaine Garth."She was also a lingerie model for various mail order companies.

Sinclair's career as an actress in videos began in 1990 with a series of softcore movies in which she played a sexy private eye named Samantha Spade.She also appeared in several hardcore films.Sinclair had a role in the Italian comedy Cous Cous (1996).Her television credits include weekly appearances on L!VE TV's The Sex Show.
Sinclair was romantically linked to Robert De Niro for two years, circa 1993-1995.

Sinclair retired from modeling and acting in late 1998 or 1999.During 2009, she came out of retirement to work on an adult daytime programme called The Pad, which airs on the Sky TV channel Tease Me.Sinclair also set up an official website.