Born in Pottsville, Pennsylvania, Averill graduated from New York University with a degree in screenwriting.

In May 2013 she signed an overall deal with CBS Television Studios, where she was the creator and executive producer of The CW science fiction teen drama Star-Crossed.

[2][3] After Star-Crossed's cancellation, she then went on to work as a Co-Executive Producer for the CW's Jane the Virgin and CBS's Pure Genius.

[4] In 2018, Averill came on board as the Co-Showrunner/Executive Producer for Netflix's adaptation of Locke & Key, which she developed for television along with Carlton Cuse and Aron Eli Coleite.

[5] In December 2020, Netflix announced it had picked up Locke & Key for a second and third season and signed Averill to a three-year overall deal.