Under Izzo, the Michigan State program has been one of the most successful in the country. Izzo has led the Spartans to the 2000 NCAA Division I National Championship, the 2009 NCAA Division I National Championship Game, seven Final Fours, and seven Big Ten Championships in his 20 years at Michigan State. The coach with the most wins in school history, Izzo's teams have earned invitations to the past 18 consecutive NCAA tournaments, in addition to setting the Big Ten record for the longest home winning streak. These accomplishments led analyst Andy Katz at ESPN to deem Michigan State the top college basketball program for the decade from 1998 to 2007 
Currently the longest tenured coach in the Big Ten Conference, Izzo, whose teams are often recognized for their rebounding prowess and defensive tenacity, has won four national coach of the year awards and maintains a considerable coaching tree—several of his former assistants are currently head coaches at other Division I schools. Izzo is just the fifth coach in Big Ten history to win seven conference titles. His immense success during the NCAA tournament has earned Izzo the nickname "Mr. March" among active coaches. In December, 2015, it was announced that Izzo was on the ballot for the first time for the Naismith Memorial Basketball Hall of Fame. On February 12, 2016 Izzo was announced as one of 14 finalists for the Naismith Memorial Basketball Hall of Fame.
After graduating from Northern Michigan, Izzo was head coach at Ishpeming High School for one season. He then took an assistant coaching job at Northern Michigan University from 1979 to 1983. Izzo was then named a part-time assistant at Michigan State in September 1983. After a short two-month stay in 1986 as an assistant coach at University of Tulsa, Izzo returned to Michigan State when assistant Mike Deane left to become head coach at Siena College. Prior to the 1990–91 season, then-current coach Jud Heathcote elevated Izzo to associate head coach. After Heathcote's retirement following the 1994-95 season and upon both his and the Michigan State Athletic Director's recommendation, Izzo was named the new head coach of men's basketball for MSU.
Izzo and John Calipari, the two highest paid college coaches in 2012, talk while scouting a blue chip recruit
Hired as head coach at Michigan State in 1995, Izzo is currently the longest-tenured basketball coach in the Big Ten Conference. He became the coach with the most wins in school history after winning his 341st game on November 29, 2009 to surpass Heathcote. In his first two seasons as head coach, Izzo went 9–9 finishing 6th and 7th in the conference and failed to make the tournament. In 1998, MSU's record in conference improved to 13–3 and Izzo won the first of his seven regular-season Big Ten championships. 1998 also saw Michigan State begin a streak of 18 straight NCAA tournament appearances, which is the 3rd longest current streak among Division I teams. Izzo has a record of 46–17 in the NCAA Tournament. In 1999, Izzo won his first of four Big Ten Tournament titles, and went to the first of Izzo's three straight Final Four appearances, joining Krzyzewski and Ben Howland as the only three coaches who have made three consecutive Final Fours since the NCAA tournament bracket expanded to 64 teams in 1985. With the instate rivalry with Michigan, Izzo's official record against the Wolverines is 22–14. Although Michigan vacated 5 of their wins in the series at the start of his head coaching career, his record against them by itself remained unchanged.
In 2000, Izzo led MSU to its second NCAA national championship with an 89–76 win over the Florida Gators. Eighty-two percent of his players who completed their eligibility left MSU with a degree. Over the years, Izzo has been pursued by the Atlanta Hawks, Chicago Bulls, Cleveland Cavaliers, and New Jersey Nets for head coaching jobs. After a brief flirtation with Cleveland, on June 15, 2010, Izzo reported to the Michigan State University's Board of Trustees that he would remain head coach of Michigan State, in which he stated he was "a Spartan for life."
Izzo fell short of obtaining his 2nd national championship on April 6, 2009, losing to North Carolina 89–72. His streak of three straight Final Four appearances from 1999 to 2001 is the third-longest of all time, and his six Final Four appearances in the years 1999–2010 were matched by no other team in college basketball.
In 2013, Izzo was voted as the fifth angriest coach in college basketball by USA Today Sports, an honor that he cherishes.
On November 26, 2015, Izzo won his 500th career game, all with Michigan State, with a win over Boston College in the Wooden Legacy. On January 28, 2016, Izzo won his 513th career game moving him into second place past Gene Keady all time for wins by a coach in the Big Ten. He trails only Bob Knight.
Izzo's teams are known for strong guard play, toughness and rebounding. Izzo is famed for his "war" rebounding drill, in which the players wear football helmets and shoulder pads. His motto is "Players Play – Tough Players Win". His other coaching philosophies include, "he doesn't determine playing time, players do" and "A player-coached team is better than a coach-coached team." Izzo is also known for scheduling extremely tough non-conference schedules as preparation for the NCAA tournament. This way the players have already played the top teams in the country and won't be fazed come March Madness.
Since he took over as head coach, sixteen players have been selected in the NBA draft. Eight of those players have been drafted in the first round. The former players under Tom Izzo who have made the NBA are: 
Izzo was head coach of the USA Basketball men's team that took 4th place at the 2003 Pan American Games. Prior to that he was assistant coach of the team that had a 5–0 record and won the gold medal at the 2001 Goodwill Games. Izzo served on the Collegiate Committee of USA Basketball's 2005-2008 Quadrennium Committees.
In 2005 and 2006, Izzo participated in Operation Hardwood, in which college coaches went to Kuwait military camps to coach basketball teams of American service members. Among the other coaches were Tubby Smith, Gary Williams, and Rick Barnes. In 2005, Izzo's team won the tournament championship.
National champion Postseason invitational champion Conference regular season champion Conference regular season and conference tournament champion Division regular season champion Division regular season and conference tournament champion Conference tournament champion