Garnett was traded to the Celtics in 2007, helping lead them to the 2008 NBA Finals and beat the Los Angeles Lakers, while also finishing in third place for the MVP award.

Living with his sister in Chicago, Garnett led Farragut to a 28–2 record and was named National High School Player of the Year by USA Today.

Garnett was named the Most Outstanding Player at the McDonald's All-American Game after registering 18 points, 11 rebounds, 4 assists, and 3 blocked shots, and then declared himself eligible for the 1995 NBA draft.

[4] Garnett's decision not to play college basketball was influenced in part by his failure to score well enough on the ACT to meet NCAA requirements for freshman eligibility.

Two weeks later at the Lakeshore Athletic Club, Fleisher ran a small tryout where Garnett dominated against older, more experienced competition.

Fleisher then set Detroit Pistons assistant John Hammond to run the drills at another workout at the University of Illinois-Chicago to gauge NBA interest.

An hour before going to the 1995 NBA draft in the Toronto SkyDome, his coach at Farragut, William (Wolf) Nelson, gave encouragement and told Garnett that he passed the last SAT test he took with a score of 970.

Garnett initially came off the bench in his rookie year, but moved into the starting lineup soon after Saunders became head coach and with the urging of Sam Mitchell.

Garnett did not immediately leap to stardom as later prep-to-pro prospects such as Amar'e Stoudemire, LeBron James and Dwight Howard would, but he did have a very respectable rookie year.

However, the Houston Rockets, led by Hakeem Olajuwon, Clyde Drexler, and Charles Barkley, proved to be too much as the Timberwolves were swept 3–0 in the first round of the 1997 NBA Playoffs.

The enormous size of Garnett's contract was considered, by numerous sports writers, a major cause of labor tensions between players and owners that led to a lockout which shortened the 1998–99 NBA season.

For the second consecutive year, the young Timberwolves bowed out of the playoffs in the first round, this time losing 3–2 to the Seattle SuperSonics and superstar point guard Gary Payton.

Although the Wolves received two-time All-Star Terrell Brandon in return, they were not able to overcome the discord and limped into the playoffs as the eighth seed with a 25–25 record.

[6] Assisted by sharpshooting rookie forward Wally Szczerbiak and steady veteran Terrell Brandon, the Wolves posted a franchise-best 50–32 record, but succumbed in the first round to the Portland Trail Blazers 3–1.

In past years, the Wolves had practically been a one-man show, but now, the Timberwolves had made two valuable acquisitions: highly talented but volatile swingman Latrell Sprewell and the seasoned two-time NBA champion Sam Cassell, who supplanted Troy Hudson at point guard.

Sprewell turned down a three-year, $21 million extension, and the Wolves wary of his injuries and age, traded Cassell for the much less effective Marko Jarić, and the team's record for 2005–06 fell to 33–49.

[27] Garnett's name was mentioned in various trade rumors involving the Chicago Bulls, Los Angeles Lakers, Golden State Warriors, Indiana Pacers, Boston Celtics, Phoenix Suns, and Dallas Mavericks.

[34] At the time of the trade, Garnett had the longest current tenure of any player in the NBA with one team, having played for the Timberwolves for his first 12 seasons (a total of 927 games).

[35][36][37] On the day the trade was announced, Garnett signed a three-year, $60 million contract extension that would start after his prior deal ran out in 2009.

[39] The combination of Paul Pierce, Ray Allen, and Garnett were almost automatically nicknamed "The Big Three" by the media, after the Larry Bird, Kevin McHale, and Robert Parish trio.

[43][44][45] Garnett passed 20,000 points for his career, becoming the 32nd player in NBA history to reach the mark,[46] with a layup in the second quarter against the Memphis Grizzlies on March 8.

They eliminated the Miami Heat, Cleveland Cavaliers, and Orlando Magic to advance to face the Los Angeles Lakers in the 2010 NBA Finals.

[60] The 2010 Finals went to a decisive seventh game in Los Angeles, where the Celtics led well into the third quarter before the Lakers mounted a comeback and held on for the victory.

Boston made the Eastern Conference Finals for the third time in five years, and faced another superstar trio in Chris Bosh, Dwyane Wade, and LeBron James of the Miami Heat.

[80] Six days later, he made his return for the Timberwolves against the Washington Wizards at the Target Center, recording five points on two-of-seven shooting with eight rebounds and two blocks in 19 minutes in his first game for Minnesota since 2007.

[83][84] On November 15, 2015, against the Memphis Grizzlies, Garnett became the fifth player in NBA history to play at least 50,000 minutes, joining Kareem Abdul-Jabbar, Karl Malone, Jason Kidd, and Elvin Hayes.

[87] On December 11, Garnett passed Malone as the NBA's all-time leader in defensive rebounds during Minnesota's 111–108 overtime loss to the Denver Nuggets.

While playing in Philadelphia, Garnett makes a trip to a New York City jewelry store owned by Howard Ratner (Adam Sandler) in the Diamond District.

[107][22][108] He met Jimmy Jam and Terry Lewis, the Grammy-winning record producers for Janet Jackson and Boyz II Men, early in his career in Minnesota and considers them as mentors.

[120] In February 2021, Simon & Schuster published Garnett's autobiography, KG: A to Z: An Uncensored Encyclopedia of Life, Basketball, and Everything in Between, written with David Ritz.