Blackmore was born c. 1987 in Perth, Australia. She is a graduate of the Western Australian Academy of Performing Arts.
In 2013, Blackmore was a finalist for the Heath Ledger Scholarship Award, which is intended to give emerging Australian talent a chance at success in Hollywood.
Blackmore's first acting credit was a recurring role as Sister Marianna in the final season of the fantasy drama series Legend of the Seeker in 2010. She is known for her roles as Natalie in the 2013 horror film Evil Dead, and as Valerie Tulle in the seventh season of The CW's supernatural drama series The Vampire Diaries.
Blackmore's other television roles include Home and Away, Beauty & the Beast, Supernatural, and TURN: Washington's Spies.