Sempronius is a town in Cayuga County, New York, United States.

[4] The town was named after a Roman military and political leader by Robert Harpur, a clerk interested in the classics.

[8] Sempronius was the birthplace of the 12th Governor of Illinois (1860-1861) John Wood on December 20, 1798.

[4] The northern part of the eastern town line borders the southern end of Skaneateles Lake and Onondaga County; the rest of the eastern town line borders Cortland County.

18.0% of all households were made up of individuals, and 5.1% had someone living alone who was 65 years of age or older.