Onondaga Hill is southwest of the city of Syracuse, in the town of Onondaga in Onondaga County, NY. It is considered a hamlet. It is located at the intersection of NYS Route 173 and NYS Route 175 on the Seneca Turnpike. The first Onondaga county courthouse, built in 1805 on Onondaga Hill, is now used as a school after the county seat moved to Syracuse in 1830.
The hamlet was the location of Onondaga's town hall until 2005.
Also on Onondaga Hill are the Onondaga Free Library and the Town of Onondaga Historical Society. On the eastern border of the hamlet, near the Syracuse city line, are the Community General Hospital and Van Duyn Home and Hospital.
Onondaga Community College’s main campus lies on the hamlet's western border.
Middle class families make up the majority of the population of Onondaga Hill.