Portis set a school freshman record with five 100-yard performances, and led the team with 838 yards and eight touchdowns on 143 carries (5.9 avg.)

Portis' sophomore season was not as successful as he lost his job to James Jackson and rushed for 485 yards and two touchdowns on 77 carries (6.3 avg.)

On December 15, 2002, Portis became the youngest player (21 years, 105 days) to score 4 touchdowns in a game in a 31–24 victory over the Kansas City Chiefs.

The very next season on December 7, 2003, Portis became the youngest player (22 years, 97 days) to score 5 touchdowns in a game in a 45–27 victory, which also happened against Kansas City.

At that time, there were criticisms regarding the trade, namely that shut-down corners like Bailey were hard to come by and that adding a second-round pick for Portis was too much and one-sided.

Critics also felt that Portis was simply a product of the Broncos' O-line scheme, and would not have much success in Washington, which was usually suited to more physical, power runners (such as Stephen Davis or John Riggins).

He had an especially tough time finding the end zone, finishing with eight total touchdowns (5 rushing, 2 receiving, and one passing).

[citation needed] Although he did not get into the end zone until the fifth game of the season, he finished strong and had 12 total touchdowns (11 rushing and one passing).

[citation needed] Portis demonstrated his speed during the 2006 Washington Redskins training camp, running a 4.26 second 40-yard dash.

[7][citation needed] However, he returned early into Washington' game against the Minnesota Vikings, where he gained 39 yards on 10 carries with one touchdown.

[8] Nagged by injuries all season, Portis suffered another setback in the first quarter of Washington's November 12 loss to the Philadelphia Eagles.

His season was highlighted by a five-week stretch in which Portis gained nearly 700 yards, ending in an October 26 victory over the Detroit Lions.

Portis led the NFL in rushing as late as November 23 before nagging injuries and limited playing time slowed him down; he gained only 281 yards in his final five games as Washington lost four of five to miss the playoffs.

Portis was still smarting from his lack of playing time in Sunday's 24–10 loss to the Baltimore Ravens, when he was removed from the game after the first series of the second half.

During his seventh year as a Redskin, Portis played only five games and tallied only 227 yards rushing throughout the season, which included two touchdowns.

[20] He officially retired on August 23 and during the press conference it was announced that he made it into the list of the 80 Greatest Redskins of All-Time.

In 2013, Portis joined former players such as Daunte Culpepper, Cadillac Williams and Art Monk in a civil lawsuit against NFL over concussion and head injuries.

[23] Portis' Washington Redskins Jersey was featured prominently in the 2007 film Transformers, worn by actor Anthony Anderson's character Glen Whitmann.

Due to mismanagement by his financial advisors that caused him to lose multiple homes, Portis filed for bankruptcy protection in December 2015,[25] and as of 2017 lived in a two-bedroom apartment in Northern Virginia.

[26] In December 2019, Portis was named as one of 12 former NFL players accused of defrauding the league's health program by filing a total of $3.9 million in false claims.

[30] In September 2021, the Department of Justice announced that Portis had pleaded guilty to obtaining $99,264 in benefits for medical equipment that was not actually provided.

"[34] That same day, he later released a statement through the Redskins' official website that claimed he did not take part in, nor condone, dog fighting.