Jim O’Day was born and raised in Worcester, Massachusetts and attended Worcester Academy and Worcester State College. Jim graduated with a Bachelor of Science, with a specialization in Urban Studies and Management. After college, Jim served as a social worker for the Department of Social Services (now Department of Children and Families), serving families in central Massachusetts for over twenty-four years. In 2007, Jim ran in a special election for an open seat in the 14th Worcester District (composed of the town of West Boylston and parts of Worcester) in a hotly contested race. He went on to win the election in April 2007 and was sworn into the House of Representatives in May of 2007.
In 2016, Representative O'Day worked with AFSCME Council 93 to form the DYS Safety Task Force within HHS. Through this, he advocates for the rights and safety of social workers. In 2017, he succeeded in passing priority legislation, An Act Protecting Department of Children and Families Social Workers’ Home Addresses, in Conference Committee.