Big Walnut High School is a public high school located in Sunbury, Ohio. It is the only high school in the Big Walnut School District. It was established in 1847.
- Founded: 1847, 1950 & the current building was built in 2022 to meet the demands of the growing district and has a student population.
- School district: Big Walnut Local School District
- Principal: Andrew Jacobs
- SRO Deputy Dave Snyder
- Athletics conference: Ohio Capital Conference
- Enrollment 1042 (fall 2021)
- Colors: Red, Scarlet
- Mascot: Golden Eagle
- Team Name: Golden Eagles
- Feeder Schools: Big Walnut Middle School
