Chiari studied medicine in Vienna, where he was an assistant to Karl Freiherr von Rokitansky (1804–1878) and Richard Ladislaus Heschl (1824–1881).

In 1878 he received his habilitation in pathological anatomy, and within a few years became an associate professor at the University of Prague.

Chiari's research dealt largely with postmortem examinations, and most of his numerous writings are the result of autopsies.

In the 1890s he described a condition involving deformities of the cerebellum, and brainstem in children with herniation of the spinal cord.

[4] Another medical term named after Chiari is the Budd–Chiari syndrome, which is ascites and cirrhosis of the liver caused by an obstruction of the hepatic veins due to a blood clot.