[2] Payette County is part of the Ontario micropolitan area.

[3] Originally a fur trapper with the North West Company, Payette was the first white man in the area in 1818.

As of the census[11] of 2000, there were 20,578 people, 7,371 households, and 5,572 families living in the county.

20.60% of all households were made up of individuals, and 9.50% had someone living alone who was 65 years of age or older.

As of the 2010 United States census, there were 22,623 people, 8,262 households, and 6,017 families living in the county.

As of the 2020 United States census, there were 25,386 people, 9,086 households, and 6,275 families residing in the county.

The county is served by three school districts:[18] Residents are in the area (but not the taxation zone) for College of Western Idaho.

[19] Like most of Idaho, Payette County voters are overwhelmingly Republican.

The county is served by the Southwest Idaho Health District.