Slowik began his coaching career in 2003 as a personnel intern for the Green Bay Packers.[4] He then returned to Wisconsin–Oshkosh in 2004 as assistant secondary coach.[4] In 2005, he became a defensive assistant with the Denver Broncos.[5] Two years later, he was named assistant special teams coach, and then in 2008, he was the team's assistant defensive backs coach.[3]
Slowik became the defensive quality control coach for the Arizona Cardinals in 2009.[6] He was promoted to outside linebackers coach in 2012.[7] He then was the team's assistant defensive backs coach and a defensive assistant from 2013 to 2014.[3] In 2015, he served as the assistant defensive line coach for the New York Jets.[8] He then joined the Cleveland Browns in 2016 as outside linebackers coach, but was one of several staff members fired after the season.[9][10] Slowik served as a defensive analyst for the Tennessee Volunteers in 2017, and spent 2018 as the head of operations at a sports training facility.[11] He became an assistant coach at the Webb School of Knoxville in 2019.[11][12]
In 2022, Slowik joined the Miami Dolphins as senior defensive assistant.[13] He was promoted to outside linebackers coach in 2023.[14] He was reported as among the candidates for the team's defensive coordinator role in 2024.[15]