Quinn was born in Texarkana, Texas. She began taking weekly acting lessons from retired director and producer Martin Beck after performing in her community's performance of The Nutcracker at age six. In the sixth grade, she auditioned at the Young Actors Studio where she performed for the program's director, Linda Seto, and representatives from the Osbrink Talent Agency. After six months of "intensive [acting] training", Quinn signed a contract with the Osbrink agency. Subsequently, she signed with Management 360. In March 2014, Quinn appeared as the voice of the sentient computer 'Fey', in the episode "Numbers" of the podcast series Welcome to Night Vale. Quinn has Irish ancestry.
^Quinn, Molly (March 22, 2011). "I have been given...". Facebook. Retrieved March 26, 2011. "I have been given permission to share the voice over project I have been doing over the last few weeks. I am the voice of "Bloom" in Nickelodeon's Winx Club that will start airing this summer. Check out this beautiful animation. Go Winx!"