11 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clayton | 1 | 34,249 | 26,698 | 3.82% | 1,988 | 17 | Town |
| Smithfield | 2 | 13,522 | 11,373 | 2.72% | 1,065 | 13 | Town |
| Selma | 3 | 7,660 | 6,363 | 2.9% | 1,416 | 5 | Town |
| Archer Lodge | 4 | 5,867 | 4,832 | 3.04% | 647 | 9 | Town |
| Benson | 5 | 4,800 | 4,002 | 2.85% | 1,519 | 3 | Town |
| Wilson's Mills | 6 | 3,092 | 2,554 | 3% | 467 | 7 | Town |
| Four Oaks | 7 | 2,890 | 2,263 | 3.77% | 933 | 3 | Town |
| Pine Level | 8 | 2,488 | 2,064 | 2.94% | 968 | 3 | Town |
| Kenly | 9 | 1,779 | 1,503 | 2.65% | 947 | 2 | Town |
| Princeton | 10 | 1,599 | 1,322 | 2.96% | 1,240 | 1 | Town |
| Micro | 11 | 563 | 463 | 3.11% | 1,054 | 1 | Town |
Clayton is the largest city in Johnston County, with a population of 34,249.
Micro is the smallest city in Johnston County, with a population of 563.
There are 11 cities in Johnston County, North Carolina.