De Roos was born in Drachten to a cobbler, but moved to Amsterdam at an early age. It was here that, between the ages of twelve and fourteen, he trained to be a lithographer. Later he studied at the Teekenschool voor Kunstambachten (The School of Drawing for the Arts and Crafts), part of the Rijksakademie. In his early years De Roos was inspired by the Arts and Crafts Movement. An example of this can be found in his edition of Kunst en Maatschappij (Art and Society (1903)). As a supporter of Ferdinand Domela Nieuwenhuis, De Roos attempted to create the ideal of ‘Art to the People’.
Between 1907 and 1947 he was employed by the Amsterdam Type foundry (known previously as N. Tetterode), where he further developed his lithographic skills. During this period he designed, a new type face, the Hollandsche Mediæval, the first Dutch made typeface for 150 years. In total De Roos designed twelve type faces, the most successful being the Hollandsche mediæval, the Egmont, the Libra and the De Roos Roman and Italic.
Archive material, as well as the Tetterode Collection both attributed to De Roos, are available at the Library of the University of Amsterdam. Further archives are available at the City Library of Haarlem, the Rijksmuseum Amsterdam, the Frans Hals Museum in Haarlem and the Museum Smallingerland in Drachten.