The Berkshire Knitting Mills were once part of a triad of companies in Reading and Wyomissing, Pennsylvania, owned by Henry Janssen (1866-1948) and Ferdinand Thun (1866-1949), known as Wyomissing Industries, which also included the Textile Machine Works and the Narrow Fabric Company. Built and incorporated between 1892 and 1906, these companies expanded rapidly between 1900 and 1930, becoming the world's largest manu­facturer of women's hosiery.

Earlier, Textile Machine Works had assembled the first American full-fashioned knitting machine (full-fashioned is a knitted garment shaped or seamed to fit close to the body.) Due to slow sales of the machine, the company set up an experimental hosiery factory to further test and perfect their machines. This pilot plant eventually became the Berkshire Knitting Mills, the largest full-fashioned knitting mills in the world. The Berkshire Knitting Mills were managed by Janssen and Thun's associate, Gustav Oberlaender (1867-1936).

The first stockings were made of cotton; later came mercerized cotton, and soon after, the industry began experimenting with silk. Rayon hosiery was introduced in 1924, and nylon was introduced in 1938, although it was not widely used until 1945.

In 1969, the mills were sold to Vanity Fair Mills, which later became an outlet store.