Katie was born and raised in Hudson, Massachusetts, the daughter of Joyce and Warren Cunningham and little sister to Ellen. She attended Hudson High School, where she played varsity field hockey and was active in the drama program, before moving to Boston to attend Simmons College, where she majored in English with a minor in Photography.

After graduation, she was hired as an Editorial Assistant at Candlewick; she worked at the company for over twenty years, eventually rising to the role of Editorial Director, and shepherded prize-winning and bestselling books that helped broaden and deepen a child’s understanding of the world. 

In 2016, Katie met Erin, the love of her life. The pair married on Cape Cod in 2018 and moved back to Katie’s hometown in 2020, shortly after the birth of their son, Jack. Katie loved being a mother, and nothing gave her more pleasure than playing pretend with him and doing silly voices to make him laugh. 

Katie was diagnosed with ovarian cancer in 2022. She underwent surgery and chemotherapy that summer before transitioning to immunotherapy treatment. For three years, she was able to spend time with her family and do the work she loved so much before complications arising from cancer ended her life on July 4th 2025. Her light will endure with those who loved her, of which there are many.