Younger sister of Mary-Kate and Ashley Olsen who emerged as a talented horror film Actress in Martha Marcy May Marlene and Silent House. She played Elle Brody in the 2014 film Godzilla and Scarlet Witch in the 2015 blockbuster Avengers: Age of Ultron.
She took ballet and singing lessons as a child and studied acting at New York University's Tisch School of the Arts and the Atlantic Theater Company.
From 2012 to 2015, she dated actor Boyd Holbrook, whom she met on the set of the film Very Good Girls. She then began dating Tom Hiddleston. In September 2017, her relationship with musician Robbie Arnett became public.
She co-starred with Josh Radnor in the 2012 indie feature Liberal Arts.