O’Shea is a lifelong resident of the 19th ward. He attended Christ the King grammar school and Mt. Carmel High School. Later, he received his degree from St. Mary’s University of Winona. In his professional career, O’Shea has served as a social worker to a director of a community center. He was an aide of former Ald. Ginger Rugai. He sits on several boards in Beverly and is a volunteer and board member for the Special Olympics Chicago.