Born in Poughkeepsie to Jamaican immigrants Lancelene and Ervin, Williams spent his first year back in his family's island nation before returning to live in Central New Jersey with his parents, sister and two brothers. His family also lived in Atlanta, Georgia and Allentown, Pennsylvania.
"By the eighth grade, " Williams would later explain, "I decided I was going to play Division I football." After transferring from Harrison High School in Kennesaw, Georgia, he attended Parkland High School in Allentown. As a senior, he had 1,913 rushing yards on 128 carries and 33 touchdowns. He earned All-State Class AAAA first-team honors as a senior running back, and was selected as The Morning Call Player of the Year. He led the Trojans to a 10-3 record in 2009.
In addition to football, he was also a standout athlete for Parkland High School's track and field team. At the 2010 PA 3A state championships, he finished third in the 100 meters, with a time of 10.76 seconds, and second in the 200 meters with a time of 22.01 seconds. He was also timed at 14.61 seconds in the 110 meter hurdles in 2009.
Considered a three-star recruit by Rivals.com, he was rated as the 44th best running back prospect in the nation. He committed to Boston College over offers from Temple, Akron and Vanderbilt.
While attending Boston College, Williams played for the its Eagles football team from 2010 to 2013. He graduated early with a degree in applied psychology and human development.
Williams's first three years at Boston College were relatively uneventful. Playing as a true freshman in 2010, Williams showed his potential, playing in all 13 games, rushing for 461 yards on 95 carries with two touchdowns. In the final regular season game of the year, playing at Syracuse, he set the school record for rushing attempts in a game, running 42 times as the Eagles beat the Orange 16-7.
As a sophomore in 2011, he continued to improve, but played less time, starting seven of 10 games and rushing for 517 yards on 124 carries with four touchdowns.
As a junior in 2012, he continued to be a reliable option, although for a pass-heavy offense, starting eight of nine games, rushing for 584 yards on 130 carries and four touchdowns. His efforts were mostly in vain though, as the Eagles continued to progressively get worse, winning 7 games in 2010, 4 in 2011, and only 2 in 2012. His three years of experience, however would pave the way for his breakout senior year and a turnaround for the Eagles team.
With a change in coaching during the offseason, Steve Addazio brought in new coordinators and a new style of offense focused heavily on the run. Williams started off the year as a potent weapon, running for 114 and 204 yards respectively in wins over Villanova and Wake Forest, and scoring once in each game. He had his worst performance of the season against a strong USC defense, managing only 38 yards. However, he bounced back against #8 ranked Florida State and ran for 149 yards as the Eagles nearly upset the eventual National Champions.
The next week during the Homecoming game against Army he exploded offensively, scoring 5 touchdowns and rushing for 263 yards, only 1 yard shy of the school's single game rushing record. He momentarily tied the record, but unfortunately lost a yard on his last rushing attempt of the game, bringing his total back down. After rushing for only 70 yards at Clemson, he gave two solid performances against UNC and Virginia Tech, rushing for 172 and 166 yards, respectively, and scoring three times. The next week at New Mexico State, Williams managed to break the single game record that he came so close to during the Army game, running for 295 yards and two scores. The win was the first road win for BC since 2011.
On the following week, playing on senior day, BC's final home game of the season against NC State, Williams broke his own record and ran for 339 yards on 42 carries, scoring twice. The performance also surpassed the ACC record, previously set at 329 yards by John Leach of Wake Forest in 1993. During the game, he also broke the school's single season record for rushing yards, finishing the day with 1,810 yards. The win made BC bowl eligible for the first time since 2010, and tripled the previous year's win total, prompting the students and fans to rush the field and celebrate with the team following the win. Williams's performance was recognized by media across the country, as he was named the Walter Camp National player of the week, as well as ACC offensive back of the week. His successes and stats as the league's leading rusher made him the front-runner for the Doak Walker Award as the nation's best running back.
After the success against NC State at home, the Eagles took on Maryland for the first of their final two road games of the season. Andre Williams had another big day, running for 263 yards and two scores, passing 2,000 yards and becoming only the 16th player in NCAA history to accomplish this feat. With this achievement, Williams became a part of the Heisman conversation.
The final game of the regular season was at 5–6 Syracuse. Unfortunately, Williams re-aggravated a right shoulder injury that he had been dealing with since the UNC game. He left the game early in the 3rd quarter and did not return, having rushed for only 29 yards for the day. Despite the disappointing end to the game, those 29 yards put Williams over 2,100 yards for the season and placed him at 9th all time in the FBS single-season rushing record books.
The Eagles final game of the season was in the 2013 Independence Bowl against the Arizona Wildcats. The game featured a matchup between the nation's two best running backs in Williams and Arizona's Ka'Deem Carey, who was a consensus All-American in 2012 as well as a finalist for the 2013 Doak Walker award, which Williams won. The game was a blowout win for Arizona, as they cruised to a 42–19 victory. Williams ran for 75 yards in his final contest as a college back, finishing with 2,177 yards on the season, 5th most all-time in the NCAA.
Williams was one of six finalists for the Heisman Trophy in 2013, and finished fourth in the voting. He was the winner of the 2013 Doak Walker Award and was named a unanimous All-American. In addition, he was a unanimous first-team All-Atlantic Coast Conference (ACC) selection and was also a finalist for the Walter Camp Award.
The New York Giants drafted Williams in the fourth round with the 113th overall pick of the 2014 NFL draft. He was released by the team on September 3, 2016.
On September 4, 2016, the San Diego Chargers claimed Williams off waivers. He was released on September 24, 2016 and was signed to the practice squad two days later. He was promoted to the active roster on December 27, 2016.
On March 9, 2017, the Chargers re-signed Williams. He was waived on September 2, 2017 and was signed to the Chargers' practice squad the next day.
Since his college years, Williams has been writing what he calls a "philosophical memoir," which is entitled " A King, a Queen and a Conscience." He expects to complete the manuscript in 2015. Williams is also trying to secure a patent for a "compression shirt" type of athletic gear that could improve backfield running.