Conrad was born in Laguna Beach, California, the daughter of Kathy and Jim Conrad. Conrad has a younger sister, Breanna (featured in Laguna Beach season three), and a younger brother named Brandon. Conrad lived with her family in Laguna Beach throughout her childhood and high school years.

During Conrad's senior year of high school, she appeared in the MTV reality series Laguna Beach: The Real Orange County. Upon graduation, she attended the Academy of Art University in San Francisco for one semester. She then transfered to the Fashion Institute of Design & Merchandising. The move, along with Conrad's new job as Teen Vogue intern was chronicled in the Laguna Beach spin-off The Hills.

The first season of The Hills premiered on MTV in May 2006. The series documents Conrad's work at Teen Vogue along with her life and the lives of her friends, including then-roommate Heidi Montag

MTV renewed The Hills for a second season, which filmed from late summer of 2006 through February of 2007. Throughout that time the friendship between Conrad and Montag deteriorated as Montag increasingly spent her time with new boyfriend, Spencer Pratt. By February 2007, Audrina Patridge another person featured on The Hills, replaced Montag as Conrad's roommate after Montag moved into a separate apartment with Pratt, effectively ending the friendship. The series recently wrapped its third season and was renewed for a fourth season.

Conrad landed an internship at Teen Vogue while filming season one of The Hills. According to Lisa Love, the West Coast editor of Vogue who evaluated Conrad for the internship position, Conrad had to interview successfully in order to get the job, "regardless of what the cameras wanted."

Conrad and her reality show appearances have been credited with improving sales of Teen Vogue. It was reported in March 2007 that, since the second season of The Hills began airing in mid-January, newsstand sales for the magazine increased by double digits over 2006 sales.

In February 2008, Conrad left her internship at Teen Vogue. She has also developed a new fashion line called "The Lauren Conrad Collection". The line debuted at Mercedes Benz LA Fashion Week at Smashbox Studios in March 2008.

In January 2007, Conrad was named the first official spokesperson of "mark.", a line created by Avon and marketed toward young women. She will partner with "mark." and collaborate in both beauty and fashion initiatives. She will be featured in the brand’s magalog (a combination magazine and catalog reaching over six million customers every month), and in the "mark." online community. A line of exclusive co-branded items are part of future plans and will be available on the website and through "mark." representatives. As of April 24, 2008, Conrad is also the national spokesperson for College Tonight.