Ewing Township is a Township in Mercer County, New Jersey, United States. As of the United States 2000 Census, the township population was 35,707. The Census Bureau's 2006 population estimate for Ewing Township is 36,916.

Ewing Township was incorporated as a township by an Act of the New Jersey Legislature on February 22, 1834, from portions of Trenton Township, while the area was still part of Hunterdon County. It became part of the newly-created Mercer County on February 22, 1838.

Although Ewing Township was officially established in 1834, the history of the region ranges back thousands of years. The earliest inhabitants of the land area today known as Ewing Township were the Lenni Lenape Native Americans. These migratory people ranged throughout New Jersey along the banks of the Delaware River, and the Township's many creeks provided rich natural resources for hunting, fishing, pottery-making, and simple farming.

When the region was first settled by European colonists around 1699, it was part of Hopewell Township, and continued under that name until the City of Trenton was established in 1719. From 1719 until 1834, the area was named Trenton Township. On February 22, 1834, the name was changed from Trenton Township to Ewing Township in honor of Charles Ewing, who was posthumously honored for his work as Chief Justice of the New Jersey Supreme Court from 1824–1832.