| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Zionsville | 1 | 34,187 | 30,786 | 1.67% | 509 | 67 | Town |
| Lebanon | 2 | 18,125 | 16,763 | 1.18% | 849 | 21 | City |
| Whitestown | 3 | 16,823 | 10,383 | 6.7% | 1,060 | 16 | Town |
| Thorntown | 4 | 1,424 | 1,434 | -0.14% | 2,014 | 1 | Town |
| Jamestown | 5 | 965 | 941 | 0.52% | 921 | 1 | Town |
| Advance | 6 | 502 | 492 | 0.4% | 852 | 1 | Town |
| Ulen | 7 | 112 | 111 | 0% | 491 | 0 | Town |
Zionsville is the largest city in Boone County, with a population of 34,187.
Ulen is the smallest city in Boone County, with a population of 112.
There are 7 cities in Boone County, Indiana.