Clarkson was born in Fort Worth, Texas and grew up in the small town of Burleson, Texas, a suburb of Fort Worth. She is the third and youngest child of Jeanne Ann Rose, a first grade teacher who is of Greek and Irish descent, and Stephen Michael Clarkson, a former engineer who is of Welsh descent. Clarkson's siblings include her brother Jason, and her sister Alyssa. When Clarkson was six years old, her parents split up after seventeen years of marriage. As a result, her brother went to live with her father, her sister went to live with an aunt, and Clarkson remained with her mother. Clarkson frequently moved around Texas while her mother managed several professions in order to support the family. The family settled in Burleson, where Clarkson's mother married her second husband, Jimmy Taylor.
While growing up, Clarkson's family had a hard time financially and often argued about money. From this experience, Clarkson learned to be financially responsible and independent at an early age. She experienced two sets of parental divorces, the first at age 6 and the second at age 19. Music became her refuge after the first divorce, but she didn't embrace it as her salvation until her teens. Clarkson first decided to become a singer when she was 13. She sang Mariah Carey's "Vision of Love" at her high school show, after which a gentleman shared some inspiring words with her: "God has given you this gift. You've got to sing. You're destined to sing." Clarkson continued to sing ever since, and soon started classical training, since her family didn't have much money .
Clarkson attended Burleson Middle School and Burleson High School. She originally wanted to become a marine biologist. In seventh grade, a teacher (Mrs. Cynthia Glenn) overheard her singing in a hallway and asked her to audition for the school choir. Clarkson told the teacher that she had never received professional vocal training. In high school, Clarkson performed in musicals such as Annie Get Your Gun, Seven Brides for Seven Brothers and Brigadoon.
Clarkson worked numerous odd jobs during and after high school, such as mowing lawns, helping her stepfather contractor build porches, and working in a movie theater starting at age 16 and until she moved to Los Angeles. She also worked for Papa John's, Subway, Starbucks, and sold vacuums door to door (her latter experience which she described with a well-intended pun: "It sucked.") .
Upon high school graduation, Clarkson was offered full scholarships to the University of Texas, University of North Texas, and Berklee, but decided against college because she had "already written so much music and wanted to try on my own. And I figured you're never too old to go to college." .
Upon graduation in 2000, Clarkson worked several jobs to finance her demo CD that she hoped to market toward record labels. She received few responses, and eventually decided to move to Hollywood to seek out other opportunities in music, one of which was a mentorship under songwriter Gerry Goffin. However, Goffin fell ill, and to make ends meet, Clarkson appeared as an extra on Sabrina, the Teenage Witch and That '80s Show among others. She played a small role in the 2002 film Issues 101. Following four months in Hollywood, Clarkson was discouraged when her apartment burned down and decided to return to Texas, where she worked as an usher in a movie theater, a cocktail waitress, Six Flags performer, telemarketer, Kirby Vacuum salesperson, and Red Bull promoter.
Clarkson currently lives with her brother Jason in Texas on 50 acres, which she calls "her sanctuary".