Bonham Carter's turn as beloved author Enid Blyton in Enid earned her the honour, while Walters received a double nod in the category - she has been nominated for her role in Mo, which saw her play British Labour Party politician Mo Mowlam, and drama A Short Stay In Switzerland.
The actresses, who both appear in the Harry Potter movie franchise, will compete with Hotel Rwanda star Sophie Okonedo for her portrayal of Winnie Mandela in Mrs Mandela.
The male acting category is also a battle of the Harry Potter stars - Kenneth Branagh (Wallander), John Hurt (An Englishman in New York) and Brendan Gleeson (Into The Storm) will go up against David Oyelowo (Small Island) for the Best Actor trophy.
Okonedo also received a nomination in the Best Supporting Actress category for drama Criminal Justice - she's up against Rebecca Hall (Red Riding 1974), Lauren Socha (The Unloved) and Imelda Staunton (Cranford).
Featured in the Best Supporting Actor category are Benedict Cumberbatch (Small Island), Tom Hollander (Gracie!), Gary Lewis (Mo) and Matthew Macfadyen (Criminal Justice).
Simon Cowell's hit TV contest Britain's Got Talent will compete with The Graham Norton Show, Harry Hill's TV Burp and Newswipe with Charlie Brooker for Best Entertainment Programme, while True Blood, Family Guy, Mad Men and Nurse Jackie are nominated for Best International Show.
The winners will be announced at a star-studded ceremony in London on 6 June (10).