|Liddell began studying Koei-Kan karate at the age of 12; the tattoo seen on his scalp reads "Koei-Kan". Liddell was a four-year starter on the football team at San Marcos High School. While growing up in Santa Barbara, he often frequented the infamous Del Playa Drive, the middle of the party scene of the college town of Isla Vista, where he often found himself in fights with drunk college students. He also claims to be 3rd generation Irish in his autobiography.
He became a Division I wrestler at California Polytechnic State University, San Luis Obispo and graduated with a Bachelor of Arts Degree in Business/Accounting in 1995. He holds an amateur kickboxing record of 20 wins and 2 losses, with 16 of his wins coming by way of knockout. When Liddell started his MMA career, he began to train in Brazilian jiu-jitsu under John Lewis in Las Vegas, Nevada.
|Liddell made his UFC debut in 1998 during UFC 17 in Mobile, Alabama, with a decision victory over Noe Hernandez. Despite a Technical submission loss to top contender Jeremy Horn shortly after, Liddell began establishing his reputation as a top contender with dominant victories over Kevin Randleman, Murilo Bustamante, Vitor Belfort, Amar Suloev, Jeff Monson, Renato Sobral and Tito Ortiz. Liddell was also the first UFC fighter currently on the roster to go fight in Pride where he represented the organization against fellow kickboxer Guy Mezger, knocking him out cold in one of the most exciting fights in the earlier days of MMA.|
|In early 2005, Liddell was a coach on the inaugural season of The Ultimate Fighter, Spike TV's reality show which featured fighters competing for a UFC contract. Liddell was the coach of Team Liddell, while then-UFC-light-heavyweight champion Randy Couture coached Team Couture. The series was a success for both Spike TV and the UFC. Both of the winners of the show, Diego Sanchez and Forrest Griffin, were members of Team Liddell and have had very successful careers in the UFC since.|