He grew up in the Sabbadini-Knorr company headquarters, located in the Kaufingerstraße in the center of Munich, and in the family house near the Lake Starnberg.

In the summer of 1880 Knorr worked with Robert Wilhelm Bunsen at the University of Heidelberg, and later assisted Adolf von Baeyer in Munich.

His habilitation followed three years later in 1885 with a thesis titled Über die Bildung von Kohlenstoff-Stickstoff-Ringen durch Ein-wirkung von Amin-und Hydrazinbasen auf Acetessigester und seine Derivate ("On the formation of carbon-nitrogen rings through the action of amine and hydrazine bases on acetoacetate and its derivatives").

In that time, during his search for quinine related compounds, Knorr discovered the unmethylated Phenazone.

After the death of Johann Georg Anton Geuther in 1889, the University of Jena was searching for a new full professor and Ernst Haeckel was sent to Würzburg to evaluate whether Knorr was qualified for the position.

In collaboration with various other chemists, Knorr proved the concept that ethyl acetoacetate existed in a keto and an enol forms.