When she was young, her parents got divorced. Hall also has half-siblings – Edward Hall, a theater director, Lucy Hall, a theater designer, Christopher Hall, a television producer, and Jennifer Caron Hall, a painter, and writer. Hall attended Roedean School, East Sussex.
She was a Head Girl in the school. Later, she joined the University of Cambridge to study English Literature but dropped out in her second year. Her professional stage debut occurred in Mrs. Warren’s Profession, for which she won the Ian Charleson Award.
She was nominated for the same award again because of her role in Peter Hall’s As You Like It. Rebecca had appearances with Andy Serkis in Avengers: Age of Ultron, Hugh Jackman in The Prestige, Toby Jones, Kevin Bacon, Oliver Pratt in Frost/Nixon.
She has also worked with Jeremy Renner in the first two series of the Avengers franchise, Thor and The Town. Rebecca is the aunt of Stephanie Clive. On September 26, 2015, Hall married Morgan Spector. The couple met while they worked together in the Broadway play, Machinal, in 2014. In 2018, they had a kid together.