Hazelton coaching career started as a defensive backs coach and interim defensive coordinator for his alma mater, Fort Lewis. In 2000, Hazelton became a grad assistant at North Dakota State where he worked closely with Bradley and held that position until after the 2001 season. After finishing his graduate program, Hazelton moved to St. Olaf College, where he worked as the Oles defensive backs coach for two seasons. In 2004, Hazelton was offered the defensive coordinator position at Missouri Southern State and held it for two years before becoming the linebackers coach at Michigan Tech in 2006.
North Dakota State
After five years of coaching elsewhere, Hazelton returned to North Dakota State as a defensive line coach in 2007. In his first year back with the Bison he helped the defense rank 18th nationally in third down efficiency and 22nd nationally in rushing defense. This was all highlighted with wins over FBS opponents Central Michigan 44–14 and Minnesota 27–21. A year later the defense led the FCS in pass defense, 5th in total defense and 19th in scoring defense. In regards to his position his players ranked 3rd nationally in sacks and 5th in tackles for a loss. 2009 was not a good year for the Bison and Hazelton. The defense forced just three interceptions while ranking 90th in scoring defense and finished 3–8. In 2010, Hazelton was promoted to defensive coordinator. His defensive unit greatly improved from 2009 as the Bison ranked 7th nationally in scoring defense and turnover margin. As well the defense ranked 15th in pass efficiency and 19th in sacks. The Bison advanced to the NCAA Football Championship Subdivision 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. In their game against the Jayhawks Hazelton's defense forced 3 turnovers and held them to under 300 yards. 2011 was a banner year for Hazelton and the Bison as they went on to win the FCS National Championship 17–6 over Sam Houston along with finishing the year with a 14–1 record. During the playoffs the Bison rode their defense as they gave up just 27 points in four games. The Bison ranked in the top 20 in six different categories including 1st nationally in points allowed and tied for 7th in takeaways with 31 in 15 games. For the second time in four years Hazelton and the Bison beat Big 10 member Minnesota 37–24.
USC
On February 12, 2012 Hazelton was hired as the linebackers coach of the USC Trojans under head coach Lane Kiffin. Hazelton replaced Joe Barry who became the linebackers coach for the San Diego Chargers on February 6, 2012.
Nevada
After just one season and less than a year with USC, Hazelton was hired by University of Nevada Wolf Pack head coach Brian Polian on January 18, 2013 to become the team's defensive coordinator.
