| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clayton | 1 | 33,871 | 26,688 | 3.79% | 1,966 | 17 | Town |
| Smithfield | 2 | 13,470 | 11,380 | 2.71% | 1,060 | 13 | Town |
| Selma | 3 | 7,621 | 6,362 | 2.9% | 1,409 | 5 | Town |
| Archer Lodge | 4 | 5,819 | 4,821 | 3.01% | 642 | 9 | Town |
| Benson | 5 | 4,795 | 4,007 | 2.9% | 1,517 | 3 | Town |
| Four Oaks | 6 | 3,082 | 2,268 | 3.49% | 995 | 3 | Town |
| Wilson's Mills | 7 | 3,076 | 2,555 | 2.98% | 465 | 7 | Town |
| Pine Level | 8 | 2,474 | 2,068 | 2.87% | 962 | 3 | Town |
| Kenly | 9 | 1,768 | 1,500 | 2.67% | 941 | 2 | Town |
| Princeton | 10 | 1,590 | 1,322 | 2.98% | 1,233 | 1 | Town |
| Micro | 11 | 553 | 458 | 2.98% | 1,036 | 1 | Town |
Clayton is the largest city in Johnston County, with a population of 33,871.
Micro is the smallest city in Johnston County, with a population of 553.
There are 11 cities in Johnston County, North Carolina.