Edgeworth Borough was founded in 1904 and took its name from the Edgeworth Female Seminary, a small school for girls that had moved to our community (then called "Sewickley Bottoms") from Pittsburgh in 1836. The Seminary was named for Maria Edgeworth, a well-known Irish writer of the period who was much admired by the founder of the Seminary, Mary Gould Olver. The seminary had an impressive curriculum and drew students from as far away as Tennessee and Georgia. Impressed by the natural beauty of the Sewickley Valley while on a visit Mary Olver decided to move her school to a setting where she could take advantage of the geographic and transportational advantages that the Sewickley Valley offered with both stagecoach and river transportation available to cities such as Pittsburgh, Cleveland, and Beaver. After the railroad was established in 1851, the stop, in the vicinity of what was to become Seminary Lane, became Edgeworth.

In the years following the Civil War, and particularly the period of 1870-1900, the availability of convenient railroad transportation made rapid changes in the economics, architecture, lifestyle and growth patterns of Leet Township and the Sewickley Valley. Local grist mills lost their importance as products could be distributed rapidly from large central mills. Perishables continued to be supplied locally, and farms were sustained in the center of what would become Edgeworth Borough. The Shield’s lands to the west of present day Edgeworth Borough completed the agrarian nature of the area even as an early commuter society was developing.

Local Transportation of the time was horse borne, and building a home was coupled automatically with a carriage house and stable. The burgeoning heavy industry of early Pittsburgh made that area less desirable as a place to live for those who could afford to commute, creating the growth impetus of Edgeworth. Communities nearest to the heavy industry became the centers supplying the man power that was essential to that industry. Edgeworth having no industrial pollution became the haven for the managers and professionals of early industrial Pittsburgh. A reputation soon followed that Edgeworth was an "upscale" residential area.

In neighboring Leet Township, increasing population slowly transformed individual horse ownership and cow herds from convenience to nuisance. Standards for early Edgeworth were required. Out of these needs arose the concept of Borough incorporation.

By the Turn of the 20th century, formation of a borough was inevitable, and active effort commenced in 1902, culminating in incorporation in 1904. It was not the large landowners of Leet Township who supported borough formation, as they were still able to sustain horses, servants and lifestyle; rather, it was the small service tradesmen making up the bulk of the freeholders. Listed were livery men, coachmen, blacksmiths, grocers, carpenters, janitors, gardeners, tinkers, tile setters, farmers, and drivers. On the other end of the scale were bankers, lawyers, doctors, brokers, architects, decorators, insurance and real estate agents, publishers and composers, engineers, and managers.

On April 27, 1903, Alexander Laughlin took a petition to the authorities of Allegheny County certifying that 101 of the 140 freeholders within the proposed new Borough of Edgeworth had signed the petition he had in hand. By February 9, 1904 approval was received, and it was decreed that the first election would be held on the third day of March 1904, between the hours of 7 a.m. and 7 p.m. Hence, the Borough of Edgeworth was born!

The population was 1,669 at the 2020 census.