Moritz Schönfeld was the author of several reference works on Germanic names and Dutch etymology which have been highly influential and are still in use today.

Schönfeld taught Dutch and geography in Meppel from 1905 to 1908, in Tilburg from 1908 to 1913, and at the municipal gymnasium in Hilversum until his retirement in 1945.

From 1917 to 1930, Schönfeld was contributed to a number of articles in the Realencyclopädie der classischen Altertumswissenschaft, published by Georg Wissowa.

Towards the end of his life, Schönfeld published Veldnamen in Nederland (1949) and Nederlandse waternamen (1955), both are important reference works on Dutch etymology.

Schönfeld contributed a large number of articles to the Nomina geographica neerlandica, of which he served as an editor for many years.