O'Connor attended Notre Dame Girls High School in Bridgeport Connecticut and lettered in three sports: softball, field hockey, and basketball.

O'Connor attended Southern Connecticut State University and in her freshman year, she was selected to play on the varsity basketball team.

[4] Teammates included her sister Eileen, Joan Bonvicini, and Sue Rojcewicz the latter of whom later joined her as a player on both the 1975 US National and 1976 Olympic teams.

In 1975, she was on the team that competed at the FIBA World Championship games in Colombia [9] where the United States compiled a 4–3 record and finished in eighth place.

[12] Shortly after the Olympics, O'Connor moved to France after being recruited by a French basketball team, Clermont UC (CUC).

[21] At the time, the team had just come up to Division One and went on to become the national champion, Championne de France, in 1980 [22] 1983, and 1984.Photo of Mary Anne – jersey 14- and her teammates in 1984 [23] After retiring from basketball, O'Connor earned her MBA from University of Hartford, Paris and worked at a French company that provided European financial data to the markets in London and New York.