McKinnie was born in Woodbury, New Jersey. He attended Woodbury High School in Woodbury, New Jersey, and played high school football for the Woodbury Thundering Herd.
McKinnie played college football for two years at Lackawanna College in Scranton, Pennsylvania. There, he gained 70 pounds and switched from his high school position as defensive lineman to offensive tackle. After junior college, he received a scholarship to transfer to the University of Miami and play for the Miami Hurricanes football team.
After redshirting in 1999, McKinnie started his junior and senior years at left tackle for the Hurricanes. During his college career, he was an extraordinary blocking tackle, not allowing a sack on a quarterback against opposition such as future NFL star Dwight Freeney from Syracuse. McKinnie was, however, penalized for holding Freeney on one play, a rare blemish on his memorable season. McKinnie received first-team All-American honors in 2000, and was recognized as a unanimous first-team All-American in 2001. Also in 2001, McKinnie was the winner of the Outland Trophy, finished 8th overall in voting for the Heisman Trophy, was the CNN Sports Illustrated "Player of the Year" and a key part of the Hurricanes' 2001 National Championship. At Miami, he was roommates with future NFL tight end Jeremy Shockey.
In the September 2006 issue of FHM magazine, McKinnie was one of five University of Miami alumni prominently featured in an article titled: "University of Miami Hit Squad: The Hurricanes are Taking Over the NFL. Deal with it." In the article, McKinnie said: "If you put together a team made up of guys playing in the NFL who come from the University of Miami, we'd be playing in the Super Bowl this season. And I think we'd win."
Bryant was inducted into the University of Miami Sports Hall of Fame as part of the Class of 2012.
McKinnie was selected seventh overall by the Minnesota Vikings in the 2002 NFL Draft. McKinnie started every game for Minnesota from 2003 to 2007, and had a streak of 80 consecutive games started.
After a 2009 loss against the Arizona Cardinals, it was reported by Tony Boselli on the Dan Patrick show that McKinnie accidentally tipped off the Vikings offensive game plan to the Cardinals. He said that the Cardinals knew when the Vikings were going to pass because of his leg. "He would have one of his legs back a little bit further" when getting in stance before the play. In 2010, McKinnie allowed a sack that injured Brett Favre and stopped his consecutive regular season start streak at 297 games.
McKinnie was selected to his first NFL Pro Bowl following the 2009 season, but didn't play in the game due to injuries in his feet and left ankle, as well as an illness he was enduring at the time. Because he was not quickly up-front with the league about these issues, the NFL front office forced him to forfeit his $22,500 check and re-pay $4,285 for other expenses.
In the summer of 2011, McKinnie was placed on the Vikings' non-football injury list for reportedly showing up to camp out of shape, according to The Star Tribune. He had finished the prior season at 360 pounds and claimed he was going to hire a trainer in the offseason to help him lose some weight. He had also been taking tennis lessons from Venus Williams during that time and claimed that the lessons were long and tired him out. He was eventually released on August 2, 2011.
After former University of Miami teammate Ed Reed vouched for him as a strong player, McKinnie signed with the Baltimore Ravens on August 24, 2011.
McKinnie saw limited playing time during the 2012 regular season, but he would go on to start at left tackle every play during the Ravens' 2012–13 NFL Playoffs run that culminated with a 34–31 Super Bowl victory over the San Francisco 49ers.
McKinnie tested free agency for a little over a month following the 2012 season, but the Ravens ultimately signed him on May 2, 2013 to a two-year deal valued at up to $7 million.
On October 21, 2013, The Ravens traded McKinnie to the Miami Dolphins for a conditional late-round draft pick for the 2015 NFL draft.
McKinnie was signed to take over immediately at left tackle for the Dolphins, who had problems with pass protection all season at the tackle positions. In his first game on October 27 against the New England Patriots, he was noted to play very sluggishly, as he had in his final games with the Baltimore Ravens. McKinnie ended the year as one of the worst offensive tackles by Pro Football Focus by the end of the year.
In October 2005, McKinnie was charged with a misdemeanor for his involvement in the Minnesota Vikings boat party scandal.
On May 26, 2006, McKinnie pleaded guilty to disorderly conduct and being a public nuisance on a watercraft in connection with the Love Boat scandal. He agreed to pay a $1,000 fine and perform 48 hours of community service. Vikings owner Zygi Wilf said, in addition to community service, he would participate in numerous service events this season. On September 9, 2006, the NFL announced that it would fine McKinnie and fellow Viking Fred Smoot one game check for the incident. For McKinnie, it amounted to approximately $41,000. A day after the fine was levied, he was given a raise and a seven-year extension of his contract worth $48 million.
In February 2008 McKinnie was arrested and charged with aggravated battery, disorderly conduct and resisting arrest without violence after a street brawl outside a Miami nightclub. Miami police said McKinnie spit in the face of a bouncer when he was removed from the club, then, after heading across the street to another establishment, returned to Club Space and argued with the bouncer, Eric Otero. McKinnie then allegedly shoved his phone in Otero's face before picking up a heavy pole and hitting him. A judge ordered McKinnie to complete 25 hours of community service and anger management classes.
On June 8, 2008 the Laureus Sport for Good Foundation welcomed Bryant McKinnie as their newest ambassador to the foundation. The foundation was inspired and established by Dr. Nelson Mandela over a decade ago with the help of some of the world's most famous athletes, among them Dan Marino, John McEnroe, Martina Navratilova, Nadia Comaneci, & Gale Sayers.
During the weekend of May 17 in Miami, McKinnie hosted the Laureus Foundation’s Third Annual Celebrity Fundraiser along with NFL Hall of Famer Marcus Allen and Olympic Track and Field Gold Medalist Edwin Moses. More than thirty greats of golf, tennis, football, hockey, and the Olympics joined McKinnie for the fundraiser which, along with the foundation’s golf and tennis invitational, raised more than $150,000 to support the formation of CampInteractive’s South Florida chapter benefitting at-risk teens.
McKinnie is also the CEO and founder of BMajor Music Group and BMajor Foundation.