From 1923 to 1925, he worked as a “research assistant” at the Reich Ministry of Finance in Berlin before moving to the University of Frankfurt am Main, initially as an assistant to Wilhelm Gerloff, from 1927 as a lecturer and from 1932 as an associate professor. Fritz Neumark was one of the first academics to be driven out of the university because of his Jewish origins; this was a consequence of the Law for the Restoration of the Professional Civil Service enacted on 7 April 1933. As early as October 1933, with the help of friends, he was able to obtain the post of Professor at the University of Istanbul, where he taught with great success until 1950 and made a decisive contribution to Atatürk’s university reforms; he also assisted the Turkish government with the introduction of income tax.
In 1952, Fritz Neumark was appointed to the Chair of Finance at the Johann Wolfgang Goethe University, a post which he held until his retirement in 1970; he was also the university's rector from 1954–55 and 1961–62. He was both respected, admired and feared by students, as his standards were high. In his research and teaching work, Neumark “popularised the concept of controlling general economic demand through the state budget”; moreover, he “made a case for his ideas of financial policy over the course of more than thirty years spent advising the steering committees of the Federal Ministry of Economics and the Federal Ministry of Finance. His role in shaping the 1967 Law on the Promotion of Stability and Growth in the Economy was by no means insignificant” (FAZ, 19 July 1990). - As an author and editor, Fritz Neumark published a wealth of books, journals and essays including Handbuch der Finanzwissenschaft (Handbook of Finance, 2nd edition 1952 ff.) and the journal Finanzarchiv (Financial Archive). He wrote about his years of exile in Germany in his autobiographical book Zuflucht am Bosporus: deutsche Gelehrte, Politiker und Künstler in der Emigration 1933–1953 (Asylum in the Bosporus: German Emigrant Scholars, Politicians and Artists 1933–1953), which was published in 1980.

Neumark received numerous awards, including the Great Cross of Merit with Star and Sash and the Wilhelm Leuschner Medal of the State of Hesse.

Fritz Neumark died in Baden-Baden on 9 March 1991. From the time of the exhibition “Jewish Emigration from Germany: a History of Expulsion” (1985), the German Exile Archive 1933–1945 remained in constant contact with Professor Neumark; he lent a number of exhibits and also gave the opening speech. His extensive estate was handed over to the German Exile Archive, where it can be used for research purposes.