Born in Garden Grove, California to Samoan parents, Asiata graduated from Hunter High School in West Valley City, Utah, where he was a standout running back for the Wolverines.
In his freshman year of high school in 2003, Asiata and the Wolverines won Hunter High's first UHSAA Class 5A football championship ever over Skyline. He was also a member the state champion basketball team that same year.
After failing to qualify out of high school, Asiata spent two seasons at Snow College in Ephraim, Utah, where he played as a running back. In his first year, he rushed for 781 yards on 144 carries (5.4 ypc) and scored five touchdowns. In 2006, his sophomore year, Asiata set a new school record for single-season rushing yards with 1,494 despite missing one game with a hamstring injury. In a four-game stretch, he rushed for 459 yards (114.8 yards a game) on 61 carries (7.5 ypc) and scored six touchdowns. Listed at 6'0" and 232 lbs, Asiata was given a three-star rating and was considered the 79th best running back in the nation according to Rivals.com. On December 11, 2006, Asiata committed to the University of Utah. He also had a scholarship offer from UNLV.
Asiata attended the University of Utah from 2007 to 2010, where he went on to become an All-Conference pick at running back. Asiata finished his career with the Utes ranked third all-time at Utah with 24 career rushing touchdowns. He scored 26 total career touchdowns (rushing and receiving) to tie for third all-time. His 1,748 career rushing yards make him the school's fourteenth-leading rusher. During his college career, he had three 100-yard games, with a high game of 156 yards in 200. In 2009, he received an NCAA medical extension to his playing clock, allowing him a sixth year in 2010.
After breaking his leg in the very first game of the 2007 season at Oregon State, Asiata returned in 2008 and played in al 13 games with one start. He led the Utes in carries with 146, rushing with a career-high 707 yards (4.8 ypc and 54.4 ypg) and touchdowns with 12, which tied for second-best in the Mountain West Conference. He also had 13 receptions for 111 yards and one touchdown and completed 2-of-3 passes out of the "Asiata Formation," with both completions going for touchdowns. His biggest outcome of the season came in Week 4 against the Air Force when he had 19 carries for 116 yards. Other big games included 85 yards against New Mexico on November 1 and 83 against San Diego State on November 15. The Utes went undefeated, going 13-0, and went on to face Alabama in the 2009 Sugar Bowl. The Utes won the game, and created controversy over the fact that the Utes were not in the BCS Championship Bowl that was played between two teams with 1 losses each. At the end of the season, Utah was the only remaining undefeated team in the country and was ranked #2 on the Associated Press (AP) Final Poll.
In his sophomore season, Asiata played and started in four games before breaking his leg during the game against Louisville. Prior to the injury, he was averaging a league-leading 101.3 yards per game and his four rushing touchdowns also led the league at the time. He finished with 74 carries for 330 yards (4.5 ypc) for an average of 82.5 yards per game and also had nine receptions for 88 yards. In the season opener game, he carried the ball 36 times for a career-high 156 yards against in-state rival Utah State. His 36 carries tied the fourth-best single-game total in school history. The following week, he had 94 yards on 20 carries against San Jose State.
In his junior season, Asiata played in all 13 games, starting seven of them at running back. He rushed 155 times for 695 yards (4.5 yards per carry). His average of 53.5 yards per game ranked ninth in the Mountain West Conference, while his nine total touchdowns (eight rushing and one receiving) tied for ninth. In Week 6, he had Utah's only 100-yard rushing game of the season with a 109-yard performance against Wyoming. On October 30, he totalled 95 yards against Air Force on 26 carries. In Week 12, he scored the game-winning touchdown against BYU on a 3-yard run. He was fourth on the team with 32 receptions for 195 yards and one touchdown.
On July 27, 2011, Asiata signed with the Minnesota Vikings as an undrafted free agent after the lockout ended and spent training camp and preseason with the team. He was released by the team during the final cuts but was then placed on the practice squad on September 5, but two days later he got cut. After no NFL teams claimed his services, he spent a couple of weeks with UFL's Omaha Nighthawks on a tryout.
After spending 2011 out of football, James Saxon (the running backs assistant) convinced head coach Leslie Frazier to give Asiata another shot in the offseason of 2012. On January 5, 2012, Asiata was re-signed by the team. At the start of the 2012 season, Asiata earned a roster spot due to his special teams abilities and was named the third running back on the Vikings depth chart, beating out other running backs Jordan Todman and Lex Hilliard.
Asiata saw action mostly as a special teamer in all 16 regular season games. In the season opener against the Jacksonville Jaguars on September 9, he caught his first career pass and returned a pair of kickoffs. On December 30, Asiata and the Vikings won their final game of the regular season against the 11-4 Green Bay Packers to put them into the Wild Card Round of the playoffs instead of the Chicago Bears.
In his second season with the team, Asiata played an integral part on special teams and stepped in at running back late in the season due to injuries. On December 15, Asiata filled in for both injured running backs Adrian Peterson and Toby Gerhart and managed three rushing touchdowns of one, one, and five yards in a 48-30 win over the Philadelphia Eagles, despite gaining just 51 yards on 30 carries. His three touchdowns tied the record for the most rushing touchdowns by a Viking in a single game and made him the first NFL player since Vikings' quarterback Daunte Culpepper to rush for three touchdowns in his first career start. The following week, he ran for a career-high 115 rushing yards on 14 carries in the season finale against the 7-8 Detroit Lions]. Asiata, while playing in 11 games and starting a game, finished the year with 44 carries for 166 yards (3.8 avg) and three touchdowns on the ground, while also hauling in five passes for 13 yards and returning two kickoffs for 28 yards.
After Adrian Peterson was suspended for the remainder of the 2014 season following Week 1, Asiata filled in for him, playing 11 games and starting 9 of those, a career-high. Asiata shared the backfield with rookie Jerick McKinnon, but he still set career-highs and led the team in rushing attempts with 164, rushing yards with 570 and rushing touchdowns with 9, which tied for the third-best mark in the league. In Week 4, Asiata tied his own hat-trick record with three touchdowns against the weak Atlanta Falcons' defense. Asiata again ran for three touchdowns during the 29-26 win over the Washington Redskins on November 2, becoming the first player in NFL history to reach nine career rushing touchdowns on the strength of three separate three-touchdown performances, per Elias Sports Bureau. In Week 17, he rushed for a season-high 91 yards on 19 carries in the season finale win against the Chicago Bears. For the 2014 season, Asiata finished with 570 yards on 164 carries (averaging 3.5 yards a carry) with a career-high 9 touchdowns, and also caught 44 passes for 312 yards and a touchdown.
In 2015, Asiata played in all 16 games for the second time in his career, and also played in his second career playoff game. With Peterson's return, Asiata came back to special teams, corralling a career-high six special teams tackles. For the most part of the season, he entered the field only on third-down situations due to his superior blocking and receiving skills, and had 29 carries for 112 yards (3.9 avg) and caught 19 passes for 132 yards (6.9 avg) in the regular season.
On March 16, Asiata re-signed with the Vikings. After Adrian Peterson was lost for a majority of the season due to a torn meniscus in Week 2 against the Green Bay Packers, Asiata earned the start for the game at Carolina in Week 3, but carried the ball just six times for 15 yards, and caught his lone target for four yards.
On May 30, 2017, Asiata signed with the Detroit Lions. On September 1, 2017, he was released by the Lions.
Asiata is of Samoan descent. He is a Mormon and has three sons and two daughters. He has a brother, Shawn, who also played as a running back for the Utes. After the Vikings released him in 2011, he went back home to Utah and got a job driving a forklift in a big warehouse. Asiata has a cousin, Isaac Asiata, who is an Offensive Lineman for the Miami Dolphins.