Tami Farrell won her first title, Miss Oregon Teen USA in 2002 and went on to win the Miss Teen USA 2003 pageant in Palm Springs, California on August 12, 2003. She also won the Miss Congeniality award at the same pageant. Farrell was the third representative of Oregon to win the pageant.

As Miss Teen USA, Farrell represented the Miss Universe Organization. Her "sister" 2003 titleholders were Amelia Vega (Miss Universe, of the Dominican Republic) and Susie Castillo (Miss USA, of Massachusetts). She gave up her title to Shelley Hennig of Louisiana in Palm Springs on August 6, 2004.

After holding the Miss Teen USA title Farrell spent the summer of 2005 in New York City, attending the summer intensive program of the New York Conservatory for Dramatic Arts in New York City and then moved to Los Angeles, California to pursue a career in the entertainment industry.

Farrell has judged a number of state pageants, including Miss Washington USA 2006 and Miss California USA 2006.

In the summer of 2008, she won the title of Miss Malibu USA 2009 and competed at the 2009 Miss California USA Pageant where she finished as first Runner up to the winner Carrie Prejean.

On June 10, 2009, she became Miss California USA 2009 after Prejean was sacked by Donald Trump. Prejean had created controversy by saying marriage should be reserved for a man and a woman during the interview portion of the Miss USA 2009 pageant. Pageant Executive Director Keith Lewis claimed that Prejean was fired due to her lack of work ethic and not because of the controversy, a claim Prejean denied.