[6][7][8][9] During his tenure with the Patriots, Belichick was a central figure as the head coach and de facto general manager during the franchise's dynasty from 2001 to 2019.

[16] He is of Croatian ancestry;[17] his paternal grandparents, Marija Barković and Ivan Biličić, emigrated from Draganić in 1897 and settled in Monessen, Pennsylvania, having changed their names to Mary and John Belichick at the suggestion of immigration officers.

[24] Belichick enrolled at Phillips Academy in Andover, Massachusetts, for a postgraduate year, with the intention of improving his grades and test scores to be admitted into a quality college.

[36][37] Belichick's defensive game plan from the New York Giants' 20–19 upset of the Buffalo Bills in Super Bowl XXV has been placed in the Pro Football Hall of Fame.

[43] In the 2013 episode of A Football Life on the Cleveland Browns relocation controversy, many sports journalists who had covered the Browns at the time had said that in retrospective, Belichick had laid the groundwork for the Ravens success in the ensuing decades including their win in Super Bowl XXXV (with Cleveland holdovers Matt Stover and Rob Burnett still with the team at that point), setting up the infrastructure by giving recently retired tight end Ozzie Newsome his first front-office job and had planned on drafting Ray Lewis in the 1996 NFL Draft if Belichick and the team stayed in Cleveland.

For his part, Belichick stated that he was able to learn from some mistakes he had made with the Browns while largely sticking to his blueprint from Cleveland when resurrecting the Patriots, such as factoring in off-the-field issues that can affect performance.

The Patriots finished with an 11–5 record and won the AFC Championship over the Jacksonville Jaguars, but they lost to the Green Bay Packers in Super Bowl XXXI amid rumors of Parcells's impending defection.

[49] Soon after this bizarre turn of events, Belichick was introduced as the Patriots' 12th full-time head coach, succeeding the recently fired Pete Carroll.

NFL Commissioner Paul Tagliabue agreed, and the Patriots gave the Jets a first-round draft pick in 2000 in exchange for the right to hire Belichick.

[52] Soon after hiring Belichick, owner Robert Kraft gave him near-complete control over the team's football operations, making him the de facto general manager as well.

[55] In 2001, the Patriots went 11–5 in the regular season, and in the playoffs defeated the Oakland Raiders (in the "Tuck Rule Game") and Pittsburgh Steelers on the way to the Super Bowl.

[61] The Patriots' 2003 season started with a 31–0 loss to the Buffalo Bills in Week 1, a few days after they released team defensive captain Lawyer Milloy.

[75][76] They then beat the San Diego Chargers the next week in the Divisional Round, before losing to the eventual Super Bowl XLI champion Indianapolis Colts in the AFC Championship by a score of 38–34.

The Patriots were upset in Super Bowl XLII 17–14 by the New York Giants, his former team, due to the defense allowing a famous play to David Tyree near the end of regulation.

After losing over 12 players to the injured reserve list, including Rodney Harrison, Adalius Thomas, and Laurence Maroney, the Patriots still managed their league-leading eighth consecutive season with a winning record, going 11–5.

[86] In 2009, with a fully healthy Tom Brady back as the starting quarterback, Belichick was able to guide the Patriots to yet another AFC East division title with a 10–6 record.

[88] In an incident dubbed "Spygate",[89] on September 9, 2007, NFL security caught a Patriots video assistant taping the New York Jets' defensive signals from the sidelines, which is not an approved location.

The NFL rules state: "No video recording devices of any kind are permitted to be in use in the coaches' booth, on the field, or in the locker room during the game."

Once again, I apologize to the Kraft family and every person directly or indirectly associated with the New England Patriots for the embarrassment, distraction and penalty my mistake caused.

[...] Part of my job as head coach is to ensure that our football operations are conducted in compliance of the league rules and all accepted interpretations of them.

We are moving on with our preparations for Sunday's game.The sanctions against Belichick were the harshest imposed on a head coach in league history until the New Orleans Saints' Sean Payton was suspended for the entire 2012 season for covering up a scheme in which bounties were paid for deliberately knocking opponents out of games.

At a mid-week press conference following a 41–14 loss to the Kansas City Chiefs, Belichick famously uttered, "We're on to Cincinnati" (referring to the Patriots' next opponent), several times in response to follow-up questions and criticisms of his team, Brady in particular.

[121][122] Super Bowl LII was Belichick's eighth title game as head coach and his eleventh overall in any capacity, which was also the Patriots' tenth appearance, all extending NFL records.

Eagles defensive end Brandon Graham strip-sacked Tom Brady to get the ball back with about two minutes to go in the fourth quarter.

[133] Following the departure of Tom Brady to the Tampa Bay Buccaneers, Belichick and the Patriots were faced with an uncertain quarterback situation for the first time in nearly two decades.

[141] Though fans criticized Belichick for his lack of warmth displayed towards his former quarterback, the two privately spoke at length in the Buccaneers locker room following the match.

[148] Two weeks later, New England upset the Buffalo Bills 29–25 to earn Belichick his 300th career regular season win as an NFL head coach.

Belichick was chosen in these roles due to his exceptional knowledge of American football, to the extent that he and fellow former head coach John Madden were specifically assigned to look over film of the earliest players selected to the team.

[215] His statement referenced the January 6 United States Capitol attack, which the House of Representatives had accused Trump of provoking when it impeached him for the second time of his presidency, and cited Belichick's "great reverence for our nation's values, freedom and democracy" in light of that event.

[216][217] A number of Massachusetts politicians, including Senator Ed Markey and Representative Jim McGovern, had previously called on him to decline after news of the award became public.