Mark Giannotti is a Partner with Marks, O’Neill, O’Brien, Doherty & Kelly’s Philadelphia office.  He is admitted to practice in Pennsylvania, the Middle District of Pennsylvania and the United States Court of Appeals of Third Circuit.  He is also a member of the Lackawanna Bar Association.

Mark graduated cum laude from Indiana University of Pennsylvania in 2000, with a dual Bachelor of Arts in Criminology and Spanish.  He then attended Duquesne University Law School, graduating in 2005.  During law school, Mark interned with the Philadelphia District Attorney’s Office. Following law school, Mark served as an Assistant District Attorney for over eight years working in both York County and Lackawanna County District Attorney’s office.  In 2008, Mark was promoted to the head of the Special Victims Unit in York County.  During the course of his employment in the public sector, Mark conducted numerous jury trials while being assigned to the Special Victims Unit, Arson Unit, Felony Drug/Gang Unit and Insurance Fraud Division.

Since joining Marks O’Neill in 2015, Mark has represented clients in professional liability, products liability, general litigation, premises liability and transportation.  He focuses his practice in general litigation and premises liability and transportation.

Mark lives in Montgomery County, Pennsylvania with his wife, Elizabeth, and their four children.

Mark G. Giannotti
Partner / Philadelphia

Phone 215-832-4270

Mark G. Giannotti PDF


  • J.D., Duquesne University, 2005
  • Dual B.A., Criminology and Spanish, Indiana University of Pennsylvania, cum laude, 2000

Bar Admissions

  • Pennsylvania
  • U.S Court of Appeals for the Third Circuit
  • U.S. District Court for the Middle District of Pennsylvania

Bar Associations

  • Lackawanna County Bar Association

Practice Areas

  • Casualty Group
  • Healthcare & Catastrophic & Excess Loss
  • Construction Accident/Construction Defect

Representative Cases



One Penn Center, 1617 John F. Kennedy Blvd., Suite 1010, Philadelphia, PA. 19103