[1][2] In 1974, Fenwick began his coaching career as the offensive coordinator for his alma mater, Pierce.
[5][6] After a 2–8 season in 1982, Fenwick briefly accepted a coaching job at El Camino College but decided to remain at Pierce.
In 1986, he left Pierce, after compiling a record of 35–18 in five seasons, to become the special teams coordinator for Cal State Northridge.
[7] After one season, he returned to junior college to become the offensive coordinator for Los Angeles Valley.
[10] In 1991, Fenwick was hired as the head football coach for Los Angeles Valley.
[23] In 2009, he returned for his second stint as the head football coach for Los Angeles Valley.
[23] From 2012 until his retirement in 2020, Fenwick served as the athletic director for Los Angeles Valley College.