Kilmacolm is a coastal parish, which lies in Inverclyde Council Area, some 4 miles (6 km) south of Port Glasgow and 5 miles (9 km) southeast of Greenock in Inverclyde.
It is located in the old county of Renfrewshire, which disappeared following the Local Government (Scotland) Act 1974.
The parish has an area of 76.7 sq. km (29.6 sq. miles). Kilmacolm has 8 neighbouring parishes; namely Erskine, Greenock, Houston & Killellan, Inverkip, Kilbarchan, Largs, Lochwinnoch and Port Glasgow.