Kimberly Brubaker Bradley was born on June 24, 1967, in Fort Wayne, Indiana. From an early age, Kimberly showed a profound love for reading, often skipping recess to engage with her school librarian. Despite her passion, she didn't initially view writing as a viable career path. Her interests also extended to chemistry, leading her to major in the subject in college. However, her educational journey at Smith, a liberal arts school, allowed her to explore various fields of interest, including writing. Encouraged by Newbery medalist Patricia MacLachlan and writer Jane Yolen, Kimberly began to hone her craft, transitioning from early attempts that she humorously describes as "very bad" to a full-fledged writing career.

Kimberly's personal life saw her marrying her high-school sweetheart, who embarked on a medical career, prompting Kimberly to initially work as a research chemist. Her writing, conducted in the nooks of her day and late into the night, eventually paved the way for a career shift from chemistry to full-time writing, coinciding with her pregnancy and the beginnings of her family life. The move to Bristol, Tennessee, for her husband's medical practice marked a significant turning point, offering Kimberly the stability and environment she needed to focus on her writing. It was during this period that her first book, Ruthie’s Gift, was under contract, a moment she recalls as "exciting."

Today, Kimberly resides on a 52-acre farm in Bristol, Tennessee, with her husband. Their family includes two grown children, an assortment of horses, two dogs, and a "surplus of cats." Her love for history and travel continues to inspire her writing. Kimberly's impactful journey in literature includes awards such as the Newbery Honor for The War That Saved My Life and Fighting Words, and the recognition of her sequel, The War I Finally Won, which received wide acclaims. Her latest work, The Night War, is set to be her twentieth publication, a testament to her enduring passion and contribution to children's and young adult literature. She uses she/her/hers pronouns and maintains a blog at One Blog Now!