Watchung () is a borough in Somerset County, in the U.S. state of New Jersey, located approximately 29 miles (47 km) west of New York City. As of the 2020 United States census, the borough's population was 6,449, an increase of 648 (+11.2%) from the 2010 census count of 5,801, which in turn reflected an increase of 188 (+3.3%) from the 5,613 counted in the 2000 census. It is located within the Raritan Valley region.

Watchung was incorporated as a borough by an act of the New Jersey Legislature on May 23, 1926, from portions of North Plainfield Township (now Green Brook Township) based on the results of a referendum held on April 20, 1926. The name "Watchung" comes from the Lenni Lenape Native Americans, meaning "high hills" or from "watschu," meaning "hill."

In 2012, Forbes.com listed Watchung as 384th in its listing of "America's Most Expensive ZIP Codes", with a median home price of $767,507.

The borough is one of the state's highest-income communities. Based on data from the American Community Survey (ACS) for 2014–2018, Watchung residents had a median household income of $153,341, almost double the statewide median of $79,363.