Harkavy was born in New York City on January 1, 1985. She is the daughter of Berta Carela and Michael Harkavy, who is the former Senior Vice President of Warner Bros. Entertainment Worldwide Publishing, Kids' WB Music, and Warner Bros. Interactive Entertainment. Her professional acting career began when she was 10 years old.
Harkavy starred in the 2010 short film Whatever Lola Wants. Nominated for a Best Actress Award at the 2011 University of Miami Canes Film Festival Harkavy is the star in the short film The Lost Doll directed by James Walhberg.
Harkavy starred in the 2011 film If You Only Knew about early-onset Alzheimer's Disease. She stars as Jessica Loren in the horror film Last Shift.
In 2016 she was cast in the fifth season of the CW show Arrow, in the recurring role of Detective Tina Boland, whose true name is revealed to be Dinah Drake, acting as the new Black Canary. She was promoted to series regular for the show's sixth season, which began airing in the Fall of 2017.
Harkavy’s first acting job was at age 10 in a commercial for the Fox Kids series Goosebumps, based on the popular horror-book series. Her first role in a major motion picture was an uncredited role in the 1995 version of A Little Princess, directed by Alfonso Cuarón.