Brimfield Township is one of the eighteen townships in Portage County, Ohio, United States. The 2020 census found 11,352 people in the township.

Portage County is a county in the U.S. state of Ohio. As of the 2020 census, the population was 161,791. Located in Northeast Ohio, Portage County is part of the Akron Metropolitan Statistical Area, which is also included in the Cleveland–Akron–Canton Combined Statistical Area. Its county seat is Ravenna and its largest city is Kent. The county, named for the portage between the Cuyahoga and Tuscarawas rivers, was created in 1807 and formally organized in 1808. In addition to the cities of Kent and Ravenna, Portage County also includes the cities of Aurora and Streetsboro, along with five villages, 18 civil townships, and several unincorporated places within those townships. Additionally, the county includes parts of the city of Tallmadge, and part of the village of Mogadore, both of which are mostly in neighboring Summit County.