The publishing business H. S. King and Company was sold in October 1877 to the firm's manager, Charles Kegan Paul. As C. Kegan Paul and Company, Paul continued the publication of popular science books commenced by King, but also built up a distinguished list of literary authors which included Tennyson, Hardy, George Meredith and Robert Louis Stevenson. The firm also published the prestigious literary journal Nineteenth Century, which ran from 1877 to 1900. In 1881, when Alfred Trench joined as partner, the firm became Kegan Paul, Trench and Company.
In a scheme devised by Horatio Bottomley, who had amalgamated printers and publishers into the ill-fated Hansard Union, the firm was amalgamated in 1889 with Trubner and George Redway to form Kegan Paul, Trench, Trubner and Company Limited, the directors of each of the former companies becoming board members and shareholders. The publishing focuses of the old firms of Kegan Paul and Trubner were soon dissipated in the large new company, which struggled financially. Charles Kegan Paul ceased to be a director in 1895, and though the company continued to publish under new directors, its reputation dwindled.
In 1912 the firm was taken over by George Routledge and Sons, where it was run as a separate company until 1947, when the two companies merged to form Routledge and Kegan Paul.
Kegan Paul was revived as an imprint in the 1980s when Associated Book Publishers purchased Routledge and Kegan Paul and sold the Routledge imprint but continued the Kegan Paul imprint for books for the Middle Eastern market.