(As of 2020) Head coach at Cecil since 1997, O'Brien has accumulated 586 wins to go along with 136 victories during a five-year stint at Keystone Junior College. O'Brien has three-times been named the Maryland Junior College Conference Baseball Coach of the Year, a three-time recipient of the NJCAA Region XX Coach of the Year, and the 2011 NJCAA Northeast District Coach of the Year.
O'Brien's coaching knowledge has impacted student-athletes far beyond Cecil's campus. O'Brien has also committed time to the ABCA, the USA National Team, Olympic teams, and the Pan-Am Games. From 2008-13, O'Brien was selected as the Maryland Junior College Baseball Coaches Association President.
A previous Tech Prep Coordinator on the academic side of Cecil's campus, O'Brien currently serves as an Academic Advisor. O'Brien has given back to the community through numerous avenues, including as a volunteer coach in the Maryland Little League.
O'Brien is married to his wife of 26 years, Lynn. The two have three children – Charles Jr., Katie, and Patrick.