Dennis Charles Mahoney grew up on the West Side of Cincinnati. He earned a Bachelor of Business Administration from the University of Cincinnati and received his law degree from Salmon P. Chase College of Law at Northern Kentucky University. Before practicing law, he worked in sales, restaurant management, and real estate, and as an investigator and officer with the Hamilton County Probation Department. After law school, he practiced on his own and later became an attorney and shareholder at O'Connor, Acciani & Levy, representing injured and disabled clients. He has served on Cheviot City Council and for five years on the Colerain Township Board of Zoning Appeals. He lives in Green Township, is a widower, and has two daughters and nine grandchildren.