Rickards made her first professional appearance in 2009, starring in the video for the Nickelback single "Never Gonna Be Alone". In early 2012 she filmed a minor role in the film Random Acts of Romance, starring Amanda Tapping and in May filmed a minor role in Flicka: Country Pride, which starred her future Arrow castmate Kacey Rohl. Her breakthrough role came in the same year with her first television casting, as Felicity Smoak in the TV series Arrow. Originally signed as a one-episode guest star, positive reaction from her co-star Stephen Amell and from Warner Brothers producer Peter Roth before the show aired, led to her being signed on as a recurring star for the rest of show's first season. The success of the character, coupled with positive fan response, led to her being made a series regular from the second season onwards. Rickards went on to portray the character in the spin-off shows to the series (collectively known as the Arrowverse) The Flash, Legends of Tomorrow and Supergirl, as well as providing the voice for the character on animated show Vixen. In 2013, she portrayed Felicity in web-based promotional tie-in series Blood Rush, sponsored by Bose, which also featured the characters of Roy Harper (Colton Haynes) and Quentin Lance (Paul Blackthorne), . In 2016, Rickards' portrayal of the character was placed at number 15 in a list of 50 Favourite Female Characters, in a poll of Hollywood professionals conducted by The Hollywood Reporter. In March 2019, Rickards announced that she would be leaving Arrow at the end of the show's seventh season.