- Lindey's Restaurant
- Logan County
- Louis B. Stokes Cleveland VA Medical Center
- Lourdes College
- Lubrizol Corp.
- Lucas County
- Luk-Aftermarket Service, Inc
- Madison County Engineer's Office
- Magruder Hospital
- Mahoning County Department of Job and Family Services and Child Support Enforcement Agency
- Malone College
- Management Reemiters of Columbus
- Marble Institute of America
- Marietta College
- Marietta Memorial Hospital
- Marketvision Research
- Marriott Cincinnati North
- Marriott Cincinnati Northeast
- Mary Rutan Hospital
- Masonic Retirement Village
- McCullough Hyde Memorial Hospital - TriHealth
- Med Flight of Ohio
- Medical deScriptions
- Medical Mutual
- Medina County Board
- MEGA II, LTD
- Memorial Hospital of Fremont
- Memorial Hospital of Union County
- Mercer County Community Hospital
- Mercy Allen Hospital
- Mercy Health - Anderson Hospital
- Mercy Health - Clermont Hospital
- Mercy Health - Fairfield Hospital
- Mercy Health - Jewish Hospital
- Mercy Health - Kings Mills
- Mercy Health - St. Vincents Medical Center
- Mercy Health - Tiffin Hospital
- Mercy Health - West Hospital
- Mercy Health - Willard Hospital
- Mercy Health Partners-Springfield
- Mercy Health Partners-Toledo
- Mercy Health St. Rita's
- Mercy Medical Center
- Mercy Memorial Hospital of Urbana
- Mercy St. Anne Hospital
- Mercy St. Charles Hospital
- MetroHealth
- Miami Valley Career Technical Center
- Miami Valley Hospital
- Midwest Stamping and Manufacturing Inc.