After a standout career at Boone County High School in his hometown, Alexander won player of the year honors for the state of Kentucky. He set records of 3,166 rushing yards and 54 touchdowns for his high school team, and accepted a scholarship offer from the University of Alabama. Alexander wasted little time in showing his prowess on the football field at the collegiate level. As a freshman in 1996, he ran for 291 yards, an Alabama single-game rushing record, and four touchdowns against LSU in Tiger Stadium. After deciding against declaring for the NFL Draft after his junior year in 1998, Alexander returned to Tuscaloosa and had a banner season. He was initially given Heisman consideration, but a sprained ankle in a game against Tennessee ended his chances of that. Nevertheless, Alexander still played a key role in leading the Tide to the SEC Championship in 1999, with his game-winning 25-yard touchdown run against the third-ranked Florida in Gainesville, and also his dominating fourth quarter performance against in-state foe Auburn in the Iron Bowl. Alexander still holds the Alabama rushing record with 3,565 yards in four seasons.

Alexander was drafted by the Seattle Seahawks with the 19th pick of the 2000 NFL Draft. He played in all 16 games his rookie year but saw limited action behind starter Ricky Watters. His fame rose the following year. In a game played on October 11, 2001 against the Oakland Raiders, he rushed for a franchise record 266 yards on 35 carries. In 2001, he led the NFL in rushing touchdowns with 14 and was tied for second with Terrell Owens with 16 total touchdowns.

In 2002, he started all 16 games en route to an NFC leading (and franchise record) 16 rushing touchdowns, four of which came in the first half of Seattle's 29 September 2002 game against the Minnesota Vikings where he also caught a touchdown pass. The five touchdowns in that half set an NFL record.

2003 was another productive year for Alexander. He rushed his way to a career high of 1,435 rushing yards and scored 16 touchdowns. Seattle also made its first playoff appearance since 2000. Alexander's success in the 2003 season earned him his first trip to Honolulu for the annual Pro Bowl.

In 2004, Alexander remained one of the key components of Seattle's offense. He finished second in the NFL in rushing yards (with 1,696) to the New York Jets' Curtis Martin by a single yard. After being passed over for a late game rushing attempt during his team's victory over the Atlanta Falcons, Alexander accused his coach Mike Holmgren of "stabbing him in the back" by denying Alexander an opportunity to win the rushing title. Alexander retracted his comments the following day, and expressed support for his coach.

Alexander has had a great deal of success in the 2005 season. In the first game, he rushed for 173 yards. Other highlights include an 88 yard touchdown run against the Arizona Cardinals on November 6, 2005, and rushing for 165 yards against the St. Louis Rams on November 13, 2005. Also, he has had two 4 touchdown games so far this year, against Arizona on September 25, 2005, and against the Houston Texans on October 16, 2005. He led the NFL in rushing yards, touchdowns, Pro Bowl votes, and points.

In 2005, he broke the franchise record for the most rushing yards in the Seattle Seahawks' history. On November 13, 2005, scoring 3 touchdowns, Alexander became the first running back in NFL history to record 15 or more touchdowns in five consecutive seasons. On November 20, 2005, in San Francisco, Shaun Alexander became the first player in NFL History to score 19 rushing or receiving TDs in only 10 games (Steve Van Buren had 18 in 1945). A feat that eventually led to him breaking Priest Holmes record of 27 total touchdowns set in 2002, and his 27 rushing touchdowns also tied Holmes for the most in a single season.

On December 11th, 2005, in Seattle's NFC West-clinching victory over the San Francisco 49ers, Alexander ran for his 9th 100 yard rushing game of the year, breaking Chris Warren's franchise record of eight 100 yard games. In the process he also set a more significant NFL record, running for 100 yards against divisional opponents in nine straight games. On December 18th, 2005, visiting the Tennessee Titans, gaining 1,600 yards for the 2nd consecutive season, Alexander ran for a Seahawks franchise record 10th 100 yard rushing game, also scoring his 24th rushing touchdown of the year, and 86th rushing TD of his career, tying him with Priest Holmes at 12th on the all-time rushing touchdown leader list. [1] Perhaps even more substantial is this, his 96th Career Touchdown, moved him into an 18th place tie with Randy Moss and Eric Dickerson on the all-time touchdown leader list [2] having already bumped Priest Holmes (94 TDs) into 21st. Shaun became the first Seahawk player to appear on the cover of Sports Illustrated, with the headline "Do you know his name?". In a fitting piece of irony, the article failed to spell his name correctly (Shawn instead of Shaun). Because of all this success he has been nicknamed "The Franchise" by his fellow players.

On January 1, 2006, in a game versus the Green Bay Packers, Alexander set the record for touchdowns in a season, 28. He also won his first NFL rushing title with 1,880 yards. In 2005, he joined Emmitt Smith, Priest Holmes, and Marshall Faulk as the only running backs to record consecutive seasons of 20 or more touchdowns. Four days later, on January 5, he was awarded him with the 2005 NFL MVP Award beating out Indianapolis Colts quarterback Peyton Manning who had won the award the previous two years. Alexander was named MVP with 19 out of a possible 50 votes. A day after receiving the MVP award, Alexander was named Associated Press Offensive Player of the Year. He received 34 votes of a panel of 50 NFL sportwriters and broadcasters. He was also named the FedEx Ground NFL Player of the Year.
Alexander, as seen on the cover of Madden NFL 07.Enlarge Alexander, as seen on the cover of Madden NFL 07.In the 2006 Divisional playoff game against the Washington Redskins Alexander suffered a concussion. Many experts began calling him "soft", and his relatively poor performance in his other two playoff games seemed to support this theory. However, in the NFC Championship Game against the Carolina Panthers he had 34 carries for 132 yards and two touchdowns, which was easily the best playoff performance of his career.

Shaun Alexander and the Seahawks lost to the Pittsburgh Steelers in Super Bowl XL on February 5th, 2006. Alexander was the leading rusher of the game with 95 yards in the loss.In March of 2006 Alexander signed an 8-year $62 million contract to remain a part of the Seattle Seahawks organization, becoming the NFL's highest paid running back in history.

Alexander will be featured on the cover of Madden NFL 07 making him the first player to appear on the covers of both EA Sports football titles, Alexander also appeared on the cover of NCAA Football 2001.