Naval Bay Subic Base in the Philippines, he is the son of Lucita Umayam Aranas and Gerald Amon Upchurch (1935–1963),[2] a Marine KC-130 crew chief.

He graduated from Flour Bluff High School in Corpus Christi in 1980 and from the University of Texas at Arlington with a Bachelor of Fine Arts degree in Drama.

[12] Phillips's big break came with the starring role in La Bamba (1987) in which he played early rocker Ritchie Valens.

Prior to his cinematic breakthrough, he starred in the Miami Vice episode "Red Tape" (March 13, 1987), portraying detective Bobby Diaz.

[14] He plays Angel David Guzman, a cholo gangster who is inspired by his math teacher, Jaime Escalante, to excel at calculus.

[17] In 1998, he starred as Cisco, the counterpart of the main character Melvin Smiley (played by Mark Wahlberg) in the comedy-action film The Big Hit.

He also played a role in the first season of the TV series 24 as secret government agent Mark DeSalvo, opposite former Young Guns star Kiefer Sutherland.

Phillips played the recurring role of FBI agent Ian Edgerton in the television series Numbers.

Phillips won the second season of the NBC reality series, I'm a Celebrity...Get Me Out of Here!, over pro wrestler Torrie Wilson.

On September 11, 2007, Phillips joined the touring troupe for Lerner and Loewe's Camelot in the role of King Arthur.

[18] Phillips had a recurring role as Colonel Telford in the Stargate Universe television series during its two-season run on the Syfy channel 2009–2011.

He played the would-be commander of the Destiny expedition, who is left behind when an accident launches an unsuspecting crew into deep space.

In June 2012, Phillips began co-starring in the television series Longmire, about a modern-day sheriff in Wyoming, played by Robert Taylor.

In December 2012, Phillips was featured in Imagine Dragons' music video for "Radioactive",[20] which eclipsed 1 billion views on YouTube.

[23] In 2015, he guest-starred in The Wiggles Rock and Roll PreSchool DVD and made guest appearances on their TV program on ABC.

After being spared by Robin Thicke ringing the Ding Dong Keep It On Bell on "WB Movie Night", he was eliminated during the "Battle of the Saved" alongside Keenan Allen as "Gargoyle".

[citation needed] Phillips co-wrote the screenplay for Trespasses and Dangerous Touch, and wrote the feature Ambition (in which he also starred on those films).

In 2019, Aethon Books announced that it would be publishing Phillips' debut novel, Tinderbox: Soldier of Indira, a science fiction retelling of the Hans Christian Andersen story of the same name.

The charges followed loud noises coming from the house he shared with his live-in girlfriend and future wife, Yvonne Boismier.

[34] On November 3, 2017, Phillips was arrested in Portland, Texas, for DWI after stopping his vehicle to ask a police officer for directions.