In 1718, William Davies and a band of Welsh settlers obtained land warrants stretching from the headwaters of the Conestoga River and reaching several miles downstream.

When Lancaster County was established in 1729, this region was given the name Caernarvon Township in honor of its inhabitants.

[5] On May 28, 2019, an EF2 tornado hit Caernarvon Township, causing substantial damage to the area.

The most prominent of these is the Pennsylvania Turnpike (I-76), which follows a northwest-southeast alignment across the western and southern portions of the township.

Interstate 176 follows the Morgantown Expressway northwestward across the central and northwestern portions of the township from its southern terminus at the Pennsylvania Turnpike.

Pennsylvania Route 10 follows Main Street and Morgantown Road along a southwest-northeast alignment through the central portion of the township.

Pennsylvania Route 23 follows Main Street along an east-west alignment across the southern portion of the township, sharing a brief concurrency with PA 10.

Finally, Pennsylvania Route 401 heads southeast along Conestoga Road from its western terminus at PA 23 in the southeastern corner of the township.