O'Shea served as a graduate assistant for Houston in 1996 before being promoted to wide receivers coach in 1997. He became tight ends coach and special teams coach in 1998 and added recruiting coordinator to those duties in 1999. In 2000, O'Shea moved to the University of Southern Mississippi, where he served as special teams coach and recruiting coordinator through 2002.
In 2003, O'Shea was a volunteer assistant as an assistant special teams coach for the Kansas City Chiefs under special teams coordinator Frank Gansz, a coach for Houston when O'Shea played there. He became a full-time assistant special teams coach for the Chiefs in 2004, spending two years in that capacity. In 2006, O'Shea joined the Minnesota Vikings as an offensive assistant, working with the wide receivers in 2007 and 2008. Also in 2008, O'Shea added assistant special teams coaching responsibilities. In 2009, O'Shea became the wide receivers coach for the New England Patriots. He is said to be an outstanding coach.