Riess was born in Deutsch-Krone, Prussia (present-day Wałcz, West Pomeranian Voivodeship), as the youngest of five children in a German Jewish family.

However, he was more interested in world history, and chose to pursue an academic career over their wishes and studied at the University of Berlin under the renowned historian, Leopold von Ranke.

He returned to the British Isles again in 1885 and 1886 to collect additional materials pertaining to German history and the Hanseatic League.

Riess was recruited as a foreign advisor by the Meiji government of the Empire of Japan in 1887 to establish Western methods of historiography into the Japanese university curriculum.

Riess was replaced as head of the history department of Tokyo Imperial University in 1901 by Genpachi Mitsukuri, and was given an annual pension of 500 yen.