Collins finished the season with 35 tackles (22 solo), one interception, five defended passes, one fumble recovery and eight kickoff returns for 181 yards.

He also contributed 54 tackles (33 solo), a fumble recovery, and the first defensive touchdown of his college career (intercepting a pass by Norfolk State University quarterback Willie Mitchell and returning it 45 yards for the score).

As a senior in 2004, Collins was an Associated Press third-team Division I-AA All-America selection and first-team All-MEAC honors at the free safety position.

[14] He completed his rookie season in 2005 with a career-high 84 combined tackles (63 solo), seven passes defensed, two forced fumbles, and an interception in 16 games and 16 starts.

[17] Head coach Mike McCarthy officially named Collins the starter to begin the regular season, opposite starting strong safety Marquand Manuel.

[19] On December 31, 2006, Collins made six solo tackles, a season-high three pass deflections, two interceptions, and scored his first career touchdown in a 26–7 victory at the Chicago Bears in Week 17.

Collins completed the 2006 season with 80 combined tackles (65 solo), ten pass deflections, three interceptions, two forced fumbles, and a touchdown in 16 games and 16 starts.

[15] The Green Bay Packers finished the 2007 season first in the NFC North with a 13–3 record and earned a first round bye and home-field advantage throughout the playoffs.

On January 12, 2008, Collins started in his first career playoff game and recorded four solo tackles in the Packers' 42–20 victory against the Seattle Seahawks in the NFC Divisional Round.

[22] The following week, he made another four solo tackles as the Packers were eliminated from the playoffs after being defeated 23–20 by the New York Giants in the NFC Championship Game.

[24] On September 14, 2008, Collins recorded two combined tackles, a pass deflection, and returned an interception by quarterback Jon Kitna for a 42-yard touchdown in Week 2 48–25 victory over the Detroit Lions.

In a Week 6 34–14 blowout win over the Indianapolis Colts, he intercepted a pass by quarterback Peyton Manning in the third quarter and returned it for his second touchdown of the season.

On October 19, 2008, he made a tackle, a season-high two pass deflections, and returned an interception for a 59-yard touchdown in a 28–27 loss at the Minnesota Vikings in Week 10.

[30][31] Collins was unsatisfied with his contract for the upcoming season and opted to skip organized team activities, but attended mandatory minicamp.

[33] The Green Bay Packers' new defensive coordinator, Dom Capers, opted to retain Collins and Bigby as the starting safeties to begin 2009.

[35] In Week 10, he collected five combined tackles, deflected two passes, and made his first career sack on quarterback Tony Romo during a 17–7 win against the Dallas Cowboys.

[35] On March 4, 2010, the Green Bay Packers placed the highest possible restricted free agent tender on Collins, to ensure they would be compensated if he signed with another team.

Collins's agent stated his client chose to immediately sign the contract as a gesture of good faith in possible negotiations for a long-term deal.

He returned an interception by quarterback Ben Roethlisberger for a 37-yard touchdown in the first quarter to give the Packers a 14–0 lead, and after the play, Collins was flagged for excessive celebration, awarding the Steelers an extra 15 yards following the kickoff.

On September 18, 2011, Collins was carted off the field on a stretcher in the fourth quarter and was immediately taken to the hospital after sustaining a neck injury while attempting to tackle Panthers running back Jonathan Stewart.

He spent the night at the hospital and returned to Green Bay the next day, where it was announced that Collins would miss the remainder of the 2011 season.

[45] On April 25, 2012, Green Bay decided to release Collins from the team citing concerns about his ability to return to football after suffering such a severe neck injury.

[51] His son Nicholas Jr. was an All-State defensive back as a freshman on the 2022 Lake Highland championship team and had already received an offer to play at his father's and grandfather's collegiate alma mater, Bethune-Cookman.