Ridley's first Oscar has come to him courtesy the moving tale of Solomon Northup, a free black man living with his wife and children in New York in 1841, who is tricked by slave traders into travelling to Washington D.C., where he is kidnapped and sold into slavery.
The film's screenplay is based on an eponymous 1853 memoir.
It won amongst nominees like 'Before Midnight' (Richard Linklater, Julie Delpy and Ethan Hawke), 'Captain Phillips' (Billy Ray), 'Philomena' (Steve Coogan and Jeff Pope) and 'The Wolf of Wall Street' (Terence Winter).
In the best writing - original screenplay, 'Her', a story about a recently divorced writer of other people's love letters, for whom the possibility of love arises from an unexpected quarter - an artificial intelligence computer operating system.
The movie has pipped 'American Hustle' (Eric Warren Singer and David O. Russell), 'Blue Jasmine' (Woody Allen), 'Dallas Buyers Club' (Craig Borten and Melisa Wallack) and 'Nebraska' (Bob Nelson) for the award.