Mike O'Hara first attracted national attention while playing volleyball for the UCLA Bruins under Coach Harry Nelson. During his stellar collegiate career, he was named All-American twice while competing on two National Championship UCLA teams.

After graduation, he continued to compete and excel, winning twelve United States Volleyball Association All-American Awards and fifteen USVBA Championships, as well as playing on the gold-medal U.S. Pan American Team in 1959 and captaining the silver-medal winning team at the Pan Am Tournament in 1963. O'Hara played on the 1960 National Team and was a team member of the first U.S. Olympic squad at the Tokyo Olympics in 1964. Twice he was voted Most Valuable Player in America by the United States Volleyball Association and was honored with the USVBA All-Time Great Volleyball Players Award in 1967.

In addition to his impressive accomplishments on indoor courts, O'Hara is one of the most outstanding players in beach volleyball history; he has 38 Open Beach Championships to his credit, third highest of all time.

After his retirement as an active player, Mike O'Hara continued to make major contributions to his sport - as a USVBA board member, as coach of the Collegiate Championship Team at Santa Monica, a national referee, a broadcaster, and as Commissioner of the International Federation of Volleyball World Series of Beach Volleyball. He served as Executive Director of the 1984 Olympics in Los Angeles and as a consultant for the Calgary and Seoul Olympic Organizing Committee. He also assisted the Barcelona Olympic Organizing Committee with preparations for the 1992 summer games.