Grant played college football at Notre Dame where he rushed for over 1,000 yards in his only year as the starting running back.

Shortly before the 2007 season, Grant was traded to the Green Bay Packers in exchange for a future sixth-round draft pick.

He played for the Washington Redskins for one month during the 2012 season before returning to the Packers to finish out the year and his NFL career.

He rushed for nearly 1,000 yards and six touchdowns in Don Bosco Prep's run to an 11–1 record and the state championship game,[3] which they lost to Holy Cross High School.

[3] In high school, Grant also played basketball and competed in track and field, where he was timed at 10.7 seconds in the 100 meter dash.

[3] In 2001, Grant went to the University of Notre Dame to play football for the Fighting Irish while majoring in sociology and computer applications.

[3] He made just a few appearances during his freshman year, playing in five games as the back-up to Julius Jones under coach Bob Davie during a 5–6 season.

[8] Grant's best game during his time at Notre Dame came against #15 ranked Air Force, as he gained 190 yards rushing and a touchdown in a 21–14 win.

[13] During his senior year, Grant was named a team captain,[14] but he split time with running back, Darius Walker.

Grant was at risk of bleeding to death and doctors at the time told him he might not regain the use of his left hand, although he did recover.

[27] Grant was traded to the Packers on September 1, 2007, in exchange for a future sixth-round draft pick,[22][28] and he played as the third-string running back behind Brandon Jackson and DeShawn Wynn for the first six games of the season.

[29] After Wynn suffered a shoulder injury in week 8, Grant took over in the second quarter against the Denver Broncos and ran for 104 yards in a 19–13 overtime win.

[26] Under starting quarterback Aaron Rodgers, the Packers qualified for the playoffs, but lost their Wild Card game to the Arizona Cardinals in overtime 51–45.

[44] During the 2010 season opener against the Philadelphia Eagles on September 12, 2010, Grant suffered a season-ending ankle injury and was placed on injured reserve after rushing for just 45 yards on eight carries.

[47] During the playoffs and Super Bowl, rookie running back James Starks emerged as a new rushing threat for the Packers.

[51] After a workout with the Chicago Bears,[51] Grant signed with the Washington Redskins on September 25, 2012, a few weeks into the season after Roy Helu was placed on injured reserve.