He is remembered for Emery's rule, which states that insect social parasites are often closely related to their hosts.

Early in his career Carlo Emery pursued a course in general medicine, and in 1872 narrowed his interests to ophthalmology.

In 1878 he was appointed Professor of Zoology at the University of Cagliari, remaining there for several years until 1881 when he took up an appointment at the University of Bologna as Professor of Zoology, remaining there for thirty-five years until his death.

Prior to 1869, his earliest works were a textbook of general zoology and papers on fishes and molluscs.

[citation needed] Emery's collections of Hymenoptera are in the Museo Civico di Storia Naturale Giacomo Doria in Genoa.