11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clayton | 1 | 32,990 | 26,698 | 3.96% | 1,915 | 17 | Town |
| Smithfield | 2 | 13,164 | 11,373 | 2.8% | 1,036 | 13 | Town |
| Selma | 3 | 7,444 | 6,363 | 2.99% | 1,376 | 5 | Town |
| Archer Lodge | 4 | 5,694 | 4,832 | 3.11% | 628 | 9 | Town |
| Benson | 5 | 4,667 | 4,002 | 2.93% | 1,476 | 3 | Town |
| Wilson's Mills | 6 | 3,002 | 2,554 | 3.06% | 454 | 7 | Town |
| Four Oaks | 7 | 2,785 | 2,263 | 3.88% | 900 | 3 | Town |
| Pine Level | 8 | 2,417 | 2,064 | 2.98% | 940 | 3 | Town |
| Kenly | 9 | 1,733 | 1,503 | 2.73% | 922 | 2 | Town |
| Princeton | 10 | 1,553 | 1,322 | 3.05% | 1,204 | 1 | Town |
| Micro | 11 | 546 | 463 | 3.02% | 1,022 | 1 | Town |
Clayton is the largest city in Johnston County, with a population of 32,990.
Micro is the smallest city in Johnston County, with a population of 546.
There are 11 cities in Johnston County, North Carolina.