Throughout his life in public service, O’Donnell has fought to bring positive change to his community, which includes Manhattan Valley, Morningside Heights, and the Upper West Side of Manhattan. He was a founding member of the New York City Chapter of Citizen Action and the Morningside Heights Historic District Committee. He also held a leadership role as the former chair of the Community Board 9 Housing and Land Use Committee and was president of a local political club on the Upper West Side. For seven years, he served as a public defender in the Brooklyn office of the Legal Aid Society before opening his own public interest law firm on the Upper West Side of Manhattan– a community practice that included tenant representation as well as civil rights litigation on issues ranging from employment discrimination to the First Amendment. He continues to be a progressive voice for the West Side who advocates for fair and sensible legislation in the State Assembly.

He currently serves as the Chair of the Subcommittee on Criminal Procedures. His Standing Committee Assignments include- Codes, Education, Judiciary, Environmental Conservation, Arts and Tourism, and Oversight, Analysis & Investigation.

He resides in Morningside Heights with his partner of 29 years, John Banta.