McKenna trained as an actress at the Central School of Speech and Drama then worked on stage in London's West End theatres before making her motion picture debut in 1952. She continued to appear in both films and on stage and in 1954/1955 was a member of the Old Vic theatre company. She was married for a few months in 1954 to actor Denholm Elliott and married again in 1957 to actor Bill Travers with whom she remained until his death in 1994.

In 1956, McKenna won the BAFTA Award for Best Actress for her performance in the film, A Town Like Alice and two years later was nominated for Best Actress again for her role as the WW II SOE agent, Violette Szabo, in 1958's Carve Her Name with Pride.

However, McKenna is best remembered for her 1966 role as Joy Adamson in the true-life film Born Free for which she received a nomination for the Golden Globe Award for Best Actress - Motion Picture Drama.

Her husband co-starred with her and the experience led them to become active supporters for wild animal rights and protecting their natural habitat. This led to McKenna and her husband becoming involved in the Zoo Check Campaign in 1984 and to their establishing the "Born Free Foundation" in 1991.

On the stage, in 1979 she won the Olivier Award for Best Actress in a British musical for her performance opposite Yul Brynner in The King and I. Over the years she appeared in more motion pictures but also was very active with television roles and on stage where she continues to make occasional appearances.

Virginia has also been responsible for helping create and furnish the Gavin Maxwell museum on (see ) Eilean Bàn, the last island home of Maxwell, an author and naturalist, most famous for his book Ring of Bright Water, on which the film of the same name was based. The title Ring of Bright Water was a line taken from a poem by Kathleen Raine.

For her services to wildlife and to the arts, in 2004 Virginia McKenna was made an Officer of the Order of the British Empire.