Blawnox is a borough in Allegheny County, Pennsylvania, United States. The population was 1,550 at the 2000 census.
The name, Blawnox, is derived from the Blaw-Knox Company, which had a manufacturing plant there providing much of the town's employment. Blawnox had previously been called Hoboken, PA, but postal regulations required that the municipality change its name since Hoboken, New Jersey had a prior claim to the name.
The town was originally founded in the late 18th century, with the name, Hoboken. Steel was the community's major industry, with the area being home to the Blaw Steel Co. and the Knox Welded and Pressed Steel Co. When the Blaw Steel Co. acquired the Knox Welded and Pressed Steel Co. in 1917, the company became known as the Blaw-Knox Steel Construction Co. and the size of Hoboken was expanded to the whole area spanned by the Blaw-Knox mill.