[1] He played college football for the Penn State Nittany Lions and was selected by the Steelers in the first round of the 1972 NFL draft.

He also scored the "Immaculate Reception" touchdown, one of professional football's most famous plays, which gave the Steelers their first playoff win.

[10] During his rookie season, Harris was a key player in one of professional football's most famous plays, dubbed the "Immaculate Reception" by Pittsburgh sportscaster Myron Cope.

[11] In the first round of the playoffs, the Oakland Raiders were leading the Steelers 7–6 with 22 seconds to play when a Terry Bradshaw pass was deflected away from intended receiver John "Frenchy" Fuqua as defender Jack Tatum arrived to tackle him.

[15] The running back tandem of Harris and Rocky Bleier combined with a strong defense to win four Super Bowls following the 1974, 1975, 1978, and 1979 seasons.

On January 12, 1975, he was the Most Valuable Player of Super Bowl IX; in that game he rushed for 158 yards and a touchdown on 34 carries for a 16–6 win over the Minnesota Vikings.

[18] Harris claimed that he extended his career and thus his contribution to the team's objectives (including four Super Bowl victories) by avoiding unnecessary contact.

[30][better source needed] In August 2008, Harris attended the 2008 Democratic National Convention, in Denver, Colorado, as part of the Pennsylvania delegation.

[37] They had one son together: Franco "Dok" Harris, who ran as a third-party candidate in the 2009 Pittsburgh mayoral election and finished in second place with 25% of the vote.

[38] Franco's brother, Pete Harris, played football for Penn State and died of a heart attack on August 15, 2006, at age 49.

He was set to attend a ceremony at halftime during a Steelers game against the Las Vegas Raiders on December 24, 2022, to retire his jersey number.

Other tributes would later come out by current and former Steelers as well as other Pittsburgh celebrities such as Joe Greene,[49] Jerome Bettis, Najee Harris, Ben Roethlisberger, Hines Ward, Tony Dungy, T. J. Watt, Trai Essex, Arthur Moats, James Conner, current Steelers head coach Mike Tomlin, Charlie Batch, Kurt Angle, Mark Madden, Tony Dorsett, Darrelle Revis, Billy Gardell, and Joe Manganiello; the Penguins and Pirates also paid tribute.

[50] The December 27, 2022, episode of Pittsburgh Dad covering the aforementioned Steelers-Raiders game (a 13-10 Steelers win) featured a tribute to Harris from the titular character.

[citation needed] Despite only playing briefly with the Seahawks, the team also acknowledged Harris's passing; other tributes from the NFL came from the Raiders, Baltimore Ravens, Emmitt Smith, Michael Irvin, Shannon Sharpe, Eric Dickerson, O. J. Simpson, Barry Sanders, Larry Csonka, Jack Youngblood, and NFL commissioner Roger Goodell.

[55][56] The Steelers held a public viewing for Harris at Acrisure Stadium on December 27, 2022, prior to the family holding a private funeral service.

In 2006, The Heinz History Center, home of the Western Pennsylvania Sports Museum, installed a life-size figure of Harris in the grand concourse of Pittsburgh International Airport, which recreates the "Immaculate Reception".

[59] On December 24, 2022, the 50th anniversary of the "Immaculate Reception", Harris became the third Steeler to have his number (32) retired;[60] the first two were Ernie Stautner (70) and Joe Greene (75).