Born in Denver, Colorado, Hagin moved with his family to San Jose, California, where he graduated from Blackford High School in 1974. He attended San Diego State University, graduating in 1979 with a bachelor's degree in radio in television.
Hagin's first play-by-play assignment was with the Oakland Athletics from 1981–84, followed by stints with the San Francisco Giants from 1987–88, the Chicago White Sox from 1989–91, the Colorado Rockies from 1993 (the team's inaugural season) to 2002, the St. Louis Cardinals from 2003-06, and the New York Mets from 2008-11.
Hagin was named Colorado Sportscaster of the Year in 2000 by the National Sportscasters and Sportswriters Association.
- Caesar, Dan (February 28, 2003). "Hagin will debut with Cardinals this Saturday". St. Louis Post-Dispatch.
- Moss, Irv (June 19, 2012). "Former Rockies announcer Wayne Hagin puts family ahead of baseball". The Denver Post.