Pre-draft Prior to the draft, Harrison worked out at
Iowa State's pro day, and was "considered a late-round prospect in a weak class of nose tackle."
New York Jets Harrison was signed by the
New York Jets as an undrafted free agent on April 29, 2012. He appeared in 5 games in 2012 but did not record a single stat that year. Following the departure of
Sione Pouha and a preseason injury to
Kenrick Ellis, Harrison was named the starting defensive tackle for the 2013 season. On October 20, 2013, Harrison recorded his first career sack when he brought down
New England Patriots quarterback
Tom Brady. During the 2013 season, Harrison started all 16 games making 66 tackles, 2 passes defended, and 1 sack. In 2014, Harrison again started all 16 games with 55 tackles. In 2015, Harrison again started all 16 games making 72 tackles, 0.5 sacks, and a forced fumble.
New York Giants Harrison signed with the
New York Giants on March 9, 2016, to a 5-year contract worth $9.25 million per year with $24 million guaranteed and $30 million over the first three years. With the Giants, Harrison was selected to be in the first-team All-Pro by the Associated Press on January 6, 2017. He was also ranked 96th on the
NFL Top 100 Players of 2017.
Detroit Lions On October 24, 2018, Harrison was traded to the
Detroit Lions for a conditional 2019 fifth-round draft pick. The condition was that the Lions would give either their own 2019 5th round pick or the 5th round pick that was previously acquired from the
San Francisco 49ers in a trade for
Laken Tomlinson, depending on which is higher. Because he was traded to the Lions before the Giants bye week and after the Lions bye week, Harrison played in 17 games during the 2018 season, the first defensive lineman to accomplish this feat. On August 21, 2019, Harrison signed a one-year, $11 million contract extension with the Lions, keeping him under contract through the 2021 season. On February 21, 2020, Harrison was released by the Lions.
Seattle Seahawks On October 7, 2020, Harrison was signed to the
Seattle Seahawks practice squad. He was elevated to the active roster on November 14 and 19 for the team's weeks 10 and 11 games against the
Los Angeles Rams and
Arizona Cardinals, and reverted to the practice squad after each game. He was promoted to the active roster on November 23. After being a healthy scratch in week 16 against the
Los Angeles Rams, Harrison requested to be released and the team waived him on December 28, 2020.
Green Bay Packers On December 30, 2020, Harrison was claimed off waivers by the
Green Bay Packers.
Retirement On November 13, 2021, Harrison announced his retirement from the NFL after nine seasons. ==NFL career statistics==