The pioneer European to see The Township of King was Étienne Brûlé in 1615, while travelling the Toronto Carrying Place. This route had long been relevant to native peoples, and would later become key to the fur-trade as well. Lake Simcoe was called "Taranto" or "Toronto" by the native people - the word was used to describe a large area, including the Humber River.

King Township was named for John King, the British undersecretary of state at the time when the township was created in 1794.

Among the first influx were Quakers from Pennsylvania, hardworking and religious people who founded the communities of Lloydtown and Schomberg. The rich soil provided lavish crops, allowing the settlers to flourish. Most of the early people formed along streams, which provided power for the mills that provided for the basic needs of the settlers. Lloydtown, Glenville, Laskay, Kettleby, and Schomberg all owe their presence to mills. These mills provided the motivation for development and growth.

In 1811, when there were perhaps two or three mills in the entire Township, a mere 206 people called King home. By the 1870s, however, the number had jumped to more than 3,000. When the usefulness of village mills faded in the latter years of the 19th century, King Township residents fell back on the soil to provide for their well-being.