County Offaly is a county in Ireland. It is part of the Eastern and Midland Region and the province of Leinster. It is named after the ancient Kingdom of Uí Failghe. It was formerly known as King's County, in honour of Philip II of Spain. Offaly County Council is the local authority for the county. The county population was 82,668 at the 2022 census.

Leinster is one of the four provinces of Ireland, in the southeast of Ireland.