Like much of Westmoreland County and surrounding areas, the region was a hunting ground for American Indians of the Six Nations.

Continental army troops built Fort Crawford, near the mouth of Pucketa Creek, in 1777.

In 1890, the Burrell Improvement Company considered the advantages of the level land south of its home in Lower Burrell, and deemed it a prime location for a city and named the area "Kensington"; this was later changed to "New Kensington" for postal reasons, to avoid confusion with the Philadelphia neighborhood of the same name.

Early achievements included a railroad station, the 9th Street bridge, a passenger boat that navigated the Allegheny River, a street car line that ran to Natrona via the West Penn Railways, the Kensington Dispatch newspaper, a fire department, hotel, opera house, and a local chapter of the YMCA.

Intended for Alcoa defense workers, it was subsequently used to rehouse displaced residents from other parts of the city.

In 1948, tenants from the Terrace decided to purchase the housing project from the U.S. government to form a co-op, managed by a board of directors, elected by representatives from the 250 units.

New Kensington maintains its own public works, fire department, police force, emergency rescue team, and water authority.

Starting in 2008, the New Kensington Redevelopment Authority moved to condemn and demolish abandoned commercial and residential properties.

The city has also instituted a Weed and Seed urban renewal program, and provided tax abatement to businesses located or opened in designated Keystone Opportunity Zones.

Parochial schools include Mary Queen of Apostles and Harvest Baptist Academy (K–12).

Since 1966, it has been located in suburban Upper Burrell Township, but retains the name Penn State New Kensington.

The PA Route 56 Arnold directional sign is visible as the car in the video travels eastbound over the 9th Street Bridge, also known as the C.L.

The city was also one of the filming locations for the movie Dogma, starring Ben Affleck and Matt Damon.