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.
^ abQuinn, Molly (2011-08-04). "Twitter / @MollyQuinn93". Twitter. Archived from the original on 2011-08-04. Retrieved 2011-08-04. "“@AADaddarion1985: @MollyQuinn93 ur last name is Celtic/Irish? So u'r of an Irish descent, right?:)” Absolutely, Molly Caitlyn Quinn"
^Quinn, Molly (2011-03-22). "I have been given... (1)". Facebook. Archived from the original on |archiveurl= requires |archivedate= (help). Retrieved 2011-03-26. "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!"