Worthington is a borough in Armstrong County, Pennsylvania, United States. The population was 778 at the 2000 census.
Worthington was laid out on a tract of land called Mt. Lorenzo by Judge James Barr in 1843–44, he choose the location due to the nearby junction of two important early stage coach routes, the east-west route from Indiana, Pennsylvania to Butler, Pennsylvania and the north-south Route from Freeport, Pennsylvania to Emlenton, Pennsylvania. It was incorporated as a borough in 1855. As the village grew into a town it variously relied upon farming and light manufacturing for its income. During the 1970s most manufacturing ceased, agriculture is still important to the region and a few light tool and die firms survive. The region also features coal, natural gas, and mineral extraction. In the 19th century an iron furnace and woolen mill were the main industrial operations, both owned and operated by Peter Graff I. The town's first settlers were a mix of eastern Pennsylvanians and newly arrived immigrants of Scotch-Irish, German and English background, other ethnic groups would arrive in the early 20th century in small numbers. Other later industries included tile block and clay drain pipe manufacturing, aluminium ladder and speciality tool and die production, limestone mining, and underground mushroom farming. The town hosts several merchants, four Protestant churches, several civic organizations (including a public library), and a community center and Municipal Complex housed in the former Jr./Sr. High School.
Worthington is located at 40°50′17″N 79°37′58″W / 40.838123°N 79.632685°W / 40.838123; -79.632685.