Ono Tomonao served as a bushō during the Sengoku period.  He came from Iinoya in the Inasa District of Tōtōmi Province.

Tomonao was the son of Ono Masanao who served as a chief retainer of Ii Naomori who governed Iinoya.  Tomonao was the younger brother of Ono Michiyoshi.

Although his father and older brother served as chief retainers, they were known as disloyal retainers for having betrayed the Ii family.  Tomonao, however, remained with the Ii family throughout his life.  He wed the daughter of Okuyama Tomotoshi.  Ii Naochika wed as his formal wife another daughter of Tomotoshi.  Later, Tomonao and his wife had a son named Inosuke (Ono Tomoyuki).  In 1560, he participated in the invasion of Owari by the Imagawa clan who at the time were the lords of the Ii family.  He then died along with Ii Naomori at the Battle of Okehazama in the fifth month of the same year.