He's a sociology major at USC. His father, Antonio Fargas, is an actor who has appeared in television (including as Huggy Bear on "Starsky and Hutch") and film ("Shaft," "Pretty Baby," "The Gambler" and "Car Wash," among others).

He ran for 6,357 yards and 82 TDs on 668 carries (9.5 avg.), all school records, in his 3-year (1995-97) career at Notre Dame High in Sherman Oaks (Calif.). As a senior, he was regarded as the nation's top prep running back. He was named a 1997 Parade All-American, USA Today All-USA first team, Super Prep National 50, The Sporting News Top 100, Super Prep All-American, Prep Star Dream Team, Prep Star All-American, ESPN/National Recruiting Advisor All-American second team, Super Prep All-Farwest, Prep Star Western Region Offensive MVP, Prep Star All-Western Region Super 30, Long Beach Press-Telegram Best in the West first team (unanimous), Cal-Hi Sports All-State first team, All-CIF Southern Section first team, All-CIF Division III Offensive MVP, Los Angeles Times All-Valley MVP, Los Angeles Daily News All-Valley MVP and All-Mission League MVP. In 1997, he rushed for 2,818 yards and 35 TDs on a school-record 313 carries (9.0 avg.). In one game, he ran for 404 yards with 6 TDs. For the second consecutive year, Notre Dame was the CIF Division III runnerup in 1997. As a junior in 1996, he gained 2,970 yards (then the third most in California history) with 38 TDs on 281 carries (10.6 avg.) while earning USA Today All-USA honorable mention, Student Sports Junior All-American, Cal-Hi Sports All-State second team, Cal-Hi Sports Junior All-State first team, All-CIF Southern Section first team, All-CIF Division III Offensive Co-MVP, Los Angeles Times All-Valley MVP, Los Angeles Daily News All-Valley MVP and All-Mission League MVP honors. He also caught 22 passes for 284 yards (12.9 avg.) with 4 scores in 1996. On one touchdown run, he somersaulted over a pile, landed on his feet and ran 40 yards to the end zone. Notre Dame was the CIF Division III runnerup in 1996. As a 1995 sophomore fullback, he rushed for 569 yards and 9 TDs on 74 carries (7.7 avg.). He also played defensive back all 3 years at Notre Dame. He also ran track at Notre Dame, winning the state 100 meters crown in 1997 (his best in the 100 was 10.47).

Fargas spent 3 seasons (1998-2000) at Michigan, first as a running back before switching to safety in the middle of the 2000 season. As a 1998 freshman, he ran for 277 yards with 1 TD on 77 carries (3.6 avg.) while appearing in Michigan's first 10 games before suffering a season-ending broken right leg in the fourth quarter versus Wisconsin. He led Michigan in kickoff returns in 1998 with 16 for 311 yards (19.4 avg.), and he also caught 1 pass for 5 yards and made 1 tackle that season. He had a team season-best 120 rushing yards on 31 carries at Northwestern. He started once (against Indiana). He was named one of the Top 10 Freshmen in the country by Sports Illustrated. He redshirted the 1999 season while rehabilitating from 3 surgeries to repair his broken leg (2 titanium rods and 12 screws were implanted in his leg in the first surgery, then 4 months later--when the leg wasn't healing properly--doctors were forced to re-break the leg and insert 2 metal plates, then the third surgery was to fix tendons in his right big toe). As a sophomore in 2000, he began the year as a backup running back and gained 85 yards on 18 carries (4.7 avg.), then asked to move to safety after 4 games (making 10 tackles and forcing a fumble). He also returned 7 kickoffs for 124 yards (17.7 avg.) in 2000. Current Trojan Tommy Huff also attended Michigan.

Fargas, who spent the previous 3 years at Michigan, transferred to USC in the spring of 2001 as a tailback, but had to sit out his 2001 junior season because of transfer rules. He spent 2001 serving as the scout team tailback and was impressive. Early in the spring of 2001, he had ligament surgery to straighten his right big toe (a residual effect from a broken leg he suffered at Michigan). He dislocated his left little finger prior to the California game.

After a year's layoff, Fargas crammed his entire USC career into his 2002 senior season. He was slated to start at tailback, but a 2002 pre-season right hamstring strain forced him out of the Auburn opener, slowed him in the next contest at Colorado and delayed his starting role. After serving as a backup the first half of the season, he started 5 late-season games (Oregon, Stanford, Arizona State, UCLA and Iowa) and made an impact. He even returned some kickoffs. Overall in 2002 while appearing in 12 games, he ran for 715 yards on 161 carries (4.4 avg.) with 7 TDs, caught 8 passes for 101 yards (12.6 avg.) and returned 7 kickoffs for 132 yards (18.9 avg.). He made the 2002 All-Pac-10 second team. He won USC's Player of the Game versus Notre Dame Award and USC's Courage Award. He was invited to play in the 2003 Senior Bowl. Fargas saw his first action as a Trojan (he had a 4-yard run) at Colorado, where he put himself into the game without the coaches knowing. He gained 24 yards on 6 tries at Kansas State, 41 yards on 17 rushes against Oregon State, 33 yards on 12 carries at Washington State and had a 1-yard carry against California. He had 22 yards on 6 tries (with a 13-yard TD. his first at USC) against Washington. At Oregon in his first start as a Trojan, he ran for a career-high 139 yards on 27 carries with a 15-yard TD. He had a team-best 43 yards on 9 carries (with a 7-yard TD) at Stanford and ran for a game-best 125 yards on 26 carries with a 3-yard TD (he also caught 2 passes for 48 yards and returned a kickoff 22 yards) versus Arizona State. He added 41 yards on 16 tries (he scored a 1-yard TD) and he had a 3-yard reception at UCLA and had 20 carries for 120 yards (both game bests), plus 4 catches for 41 yards and a 26-yard kickoff return, against Notre Dame. He had a game-best 122 yards on 20 carries (with touchdowns of 4 and a career-long 50 yards) against Iowa in the Orange Bowl, plus he caught a 9-yard pass and returned 2 kickoffs for 33 yards.

Justin Fargas was selected by the Oakland Raiders in the third round of the 2003 NFL Draft.