 We detected highly pathogenic avian influenza A, H5N1, clade 2.3.4.4b virus in a domestic cat that lived near a duck farm infected by a closely related virus in France during December 2022. Enhanced surveillance of symptomatic domestic carnivores in contact with infected birds is recommended to prevent further spread to mammals and humans. This article was authored by Francois Xavier Bryant, Florence Suchaud, Isabel Pierre, and others.