Harndt studied medicine and dentistry in Berlin from 1920 to 1926 and went on to work at the Institute of Dentistry at Friedrich-Wilhelms-Universität starting in 1927. In 1938, he was given a position as a lecturer – two years late, because of his “political unreliability.”
In May of 1950, Harndt became a professor and the provisional director of the Institute of Dentistry, but he left that position in November 1950 for political reasons and moved to Freie Universität in 1951.
In 1956, Harndt became a professor of dentistry and oral and maxillofacial surgery at Freie Universität and took over the leadership of the Polyclinic for Dentistry and Oral and Maxillofacial Surgery.
Harndt was named an honorary member of a large number of dental societies and associations and received many international awards and distinctions.
In 2001 – the year marking the 100th anniversary of Harndt’s birth – the Berlin Association of Dentists (Zahnärztekammer) introduced the Ewald Harndt Medal in honor of its namesake. The medal has been awarded every year since then in recognition of individuals or organizations that have rendered extraordinary service to the profession of dentistry.