Newlin Township was the hometown of explorer Josiah Harlan and Lenape healer Hannah Freeman.

Physician and Civil War nurse Hettie Kersey Painter grew up in Newlin.

[4][5] The township was named for Nicholas Newlin (1630–1699), who received a deed from William Penn.

In 1704, his son Nathaniel (1663–1729) and his wife Mary built a water-powered gristmill along the West Branch of Chester Creek.

At the 2010 census, the township was 95.0% non-Hispanic White, 0.6% Black or African American, 0.9% Asian, and 0.6% were two or more races.

PA 842 follows Unionville Wawaset Road along a southwest-northeast alignment through the southeastern part of the township.