After serving as captain of several torpedo boats, he commanded in turn the light cruisers Lübeck in 1911 and Cöln in 1912–13.

As captain of the battlecruiser Von der Tann in 1916–17, Zenker saw action in the Battle of Jutland on 31 May – 1 June 1916.

He was appointed to the North Sea area command in 1918, holding this post when the German war effort collapsed in November 1918.

His tenure as head of the Reichsmarine saw the beginning of the rebuilding of the German fleet with the construction of light cruisers and torpedo boats and the planning of Deutschland class ships, later built as the Deutschland, Admiral Scheer, and Admiral Graf Spee.

His son, Karl-Adolf Zenker (1907-1998), held the office equivalent to Chef der Marineleitung—Inspector of the Navy—in the West German Bundesmarine from 1961 to 1967.