Johnson County Flag

Johnson County

State:
Kansas
County Seat:
Olathe

Johnson County's estimated 2026 population is 645,940 with a growth rate of 1.07% in the past year according to the most recent United States census data. Johnson County is the largest county in Kansas. The 2010 population was 545,681 and has seen a growth of 18.37% since that time.

645,940
Total Population
1,363
Population Density (mi²)
1
Population Rank (State)
6.8K 1.07%
Annual Population Growth

Johnson County Population

Demographics

Economics and Income Statistics