In 2000, he became a graduate assistant for North Dakota State under defensive coordinator Gus Bradley.
[1] After finishing his graduate program, Hazelton was hired by St. Olaf as the defensive backs coach, a position he held for two years.
[1] He left St. Olaf in 2004 to become the defensive coordinator for Missouri Southern under head coach John Ware.
[1] The Bison advanced to the NCAA Football Championship Subdivision (FCS) playoffs in 2010 for the first time in school history during Hazelton's inaugural season as defensive coordinator which included a win over Big 12 member Kansas 6–3.
[5][dead link] The Bison ranked in the top 20 in six different categories including 1st nationally in points allowed (12.73 ppg) and tied for seventh in takeaways with 31 in 15 games.
On January 18, 2013, after just one season with USC, Hazelton was hired by Nevada to be the defensive coordinator under head coach Brian Polian.
[9] Hazelton was hired by Kansas State under head coach Chris Klieman to be the defensive coordinator.
[11] On February 28, 2020, Hazelton was announced as Michigan State's defensive coordinator in the team's first season under head coach Mel Tucker.