Katie Alender (rhymes with "calendar") grew up in South Florida. She is the third of four children, with three girls and a boy, raised by very loving and encouraging parents. She attended high school at the Palm Beach County School of the Arts, studying Communication Arts. From there, she went on to the Florida State University Film School, which led her to Los Angeles, where she worked in TV production and development before becoming an author.

She enjoys writing, reading, sewing (especially quilts), and spending time with her husband, daughters, and dogs, Scooter and Frodo. Her first brush with publication was the article "So You Want to Live On Mars?" published in Sassy magazine in December 1991.

In 2009, her first book, Bad Girls Don’t Die, was published by Hyperion, followed by two sequels, From Bad to Cursed (2011) and As Dead as It Gets (2012). She then published three books with Scholastic, Inc.: Marie Antoinette, Serial Killer (2013), Famous Last Words (2014), and The Dead Girls of Hysteria Hall (2015). In 2020, she published The Companion for Penguin. In spring of 2021, The Companion won the Edgar Award for Best Young Adult Novel.

She is represented by Matthew Elblonk of DeFiore and Company and is a member of SCBWI (the Society of Children’s Book Writers and Illustrators), MWA (Mystery Writers of America) and ITW (International Thriller Writers).

Despite not liking scary books or movies, her own books are often considered scary by many. A fun fact is that she loves talking about herself in the third person.