6 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ashland | 1 | 20,864 | 21,589 | -0.69% | 1,944 | 10.73 | City |
| Westwood | 2 | 4,540 | 4,654 | -0.31% | 1,215 | 3.74 | CDP |
| Catlettsburg | 3 | 1,714 | 1,773 | -0.7% | 1,285 | 1.33 | City |
| Cannonsburg | 4 | 1,076 | 676 | 1.41% | 617 | 1.74 | CDP |
| Ironville | 5 | 919 | 1,028 | 7.11% | 1,183 | 0.78 | CDP |
| Bellefonte | 6 | 868 | 913 | -1.03% | 985 | 0.88 | City |
Ashland is the largest city in Boyd County, with a population of 20,864.
Bellefonte is the smallest city in Boyd County.
There are 6 cities in Boyd County, Kentucky.