Mrs. O’Neill’s public health career has its roots in health promotion and education and progressed to project management and administration. O’Neill is known for her ability to lead co-workers, pull resources, and negotiate with a diversity of individuals. Since March 2006, O'Neill has served as the Howard County Deputy Health Officer. During that time she is credited with overseeing reorganization efforts that saved almost $1.5 million and increased services to Howard County residents. Prior to working for Howard County she worked for the Baltimore City Health Department where she served as Quality Assurance Manager for the Ryan White Program, Administrator then Acting Assistant Commissioner of the Division of Maternal and Child Health and as the Health Commissioner's Chief of Staff.

O'Neill served on multiple community boards including Baltimore HealthCare Access and the Baltimore City Social Services Commission. She received her undergraduate degree from State University of New York at Cortland College and Master of Public Health from the University of South Carolina Norman J. Arnold School of Public Health.