Before moving to California, Kristin Cavallari lived in Connecticut, St. Louis, Missouri, Colorado and Barrington, Illinois. Once her parents divorced, her father moved to Laguna Beach, California with her younger brother Gabriel Zamora Cavallari and Kristin Cavallari moved with her mother to Colorado. After having severe problems with her step brother in Illinois, Kristin's mother finally allowed her to move to California to be with her dad and brother. Upon arriving, Kristin was immediately enrolled at Santa Margarita Catholic High school, a private Catholic High School but attended driver's education class elsewhere. While attending her driver's ed classes, she met Melissa Martinez and Alex Murrell with whom she became good friends and after weeks of begging her father, she was allowed to attend Laguna Beach High School.

Kristin went on a double date with a friend and a boy at her new high school who she had a crush on. However, while on the date she realized she wanted her friend's date Stephen Colletti. Since her friend wasn't interested in Stephen, there was no problem when the chemistry between Kristin and Stephen escalated and they began dating. Kristin and Stephen had a very intense relationship. They dated for two years in high school but were involved in a love triangle with Stephen's childhood friend Lauren Conrad who also liked Stephen. During this time, Kristin continued to date other boys. From this time Kristin and Lauren became enemies. After being on and off for two years Kristin ended the relationship with Stephen for good during Laguna Beach Season Two after he returned from College and she had moved on.

After her stint on reality tv was over, Kristin headed to L.A where she attended Loyola Marymount University for a short while before landing a hosting gig on "Let's Get This Party Started" and several other ad campaigns including "Until There's A Cure," Bongo, and PETA. Although her hosting gig was short lived, she has continued to have great luck in Hollywood landing both a guest role on the popular television series Veronica Mars, a lead spot in a music video with Teddy Geiger, photo spreads in Blender and Rolling Stone magazine, and movie roles in Fingerprints and Spring Breakdown.