Valley Township was formed in 1852 by a decree of the court; it was composed of a considerable slice off the south end of West Caln and a small slice off the south end of West Brandywine. It is half its original size being reduced in size first by the incorporation of the Borough of Coatesville in 1867 and in 1868, by the creation of the Township of Caln.

In 1816, Dr. Charles and Rebecca Pennock Lukens moved to Coatesville and took over the operations of the Brandywine Mills considered the first boilerplate rolling mill in Pennsylvania. In 1890 it evolved into the Lukens Iron and Steel Company named for Rebecca Lukens and was located in Valley Township and Coatesville; Mittal Steel now own the Company.

During the 1830's Valley Township had blacksmith shops that were located in the Rock Run section of the township. They were demolished in 1939 due to the expansion of the Coatesville Plate Washer Company.

Valley was the home of many farms, which made it a rural community. The Scott and Rambo Farms were two of the largest farms in the area, which formed the Westwood section of the township.

The White Oak Farm was the site of an old Indian burial ground that belonged to the Lenni-Lenape Indians who inhabited all of Chester County.

The old Rainbow Farm was given its name because of the way the land slanted or curved in the shape of a rainbow. There were several buildings constructed which included an inn, the Rainbow school, and a store which are here today located on the West Lincoln Highway. The old school house became the Rainbow Archery Shop and is now the Domino Pizza Shop.

The old Passtown School once a one-room schoolhouse was enlarged and refurbished; it is now the Valley TownshipMunicipal Building, Passtown School was named for the trail called "Hands Pass" a Revolutionary War Era heirloom. It was there that General Edward Hand, on of Washington's staff officers, and a small company of soldiers who were scouting the area came face to face with a group of Hessians from the British camp. The Hessians immediately retreated thus making an exchange of gunfire unnecessary. The pass was named for General Hand, who was from Lancaster, because of the bravery shown by him and his men. The pass was widened to accommodate the Lincoln Highway (Route 30) which passes from east to west through Hayti and divides the township.

In 1894, a decision made by a special jury prevented the now defunct "Rockdale School System", located in the western portion of the township, from being annexed by Sadsbury that secured the present boundaries of the township.

In the early 1900's, a trolley ran from Coatesville to Parkesburg through Westwood on Valley Road. The introduction of busses brought its demise in the late 1930's. Just below Rock Run, the Penn Central Railroad which runs East and West Crosses the Reading Railroad which runs North and south. The Reading, once a passenger line, now only handles freight.

The G.O. Carlson Airport, now the Chester county Airport, has grown from a small entity to becoming the largest and busiest airport in the county.

The township has several older communities like Rock Run, Hayti, Coatesville Heights, and Westwood. It is still the home of a couple of farms and the Brandywine River flows through the Rock Run and West wood sections of the township. The Sucker Run, which flows through Westwood, provided water to the steel mill.

Today, Valley Township is experiencing a growth spurt with many new developments that are under construction or will be under construction in the near future. The opening of the Route 30 Bypass in 1966 made the township more accessible. Valley Township will soon become one of the fastest growing communities in the county.