Ontario County may refer to:

• Ontario County, New York, United States
• Ontario County, Ontario, a former county in Canada
• Bradford County, Pennsylvania, United States, known as Ontario County until 1812

• Ovays Azizi
• Ovazemba
• OvaZemba people
• OVB AIrport
• OVCAR-3
• OVCAR-8
• OV card
• Ovcar, Mitrovica
• OV certificate
• Ovcha Kupel
• Ovcha Kupel Stadium
• OV Challenger
• Ovcharenko, Victor
• Ovcharov
• Ovcharova
• Ovcharow
• Ovchinin
• Ovchinino
• OV Columbia
• OVC project
• Ovdat
• OV Discovery
• Ovdog Khudag coal mine
• OVe
• Ove Andersen (politician)