| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Jacksonville | 1 | 72,606 | 73,158 | -0.17% | 1,455 | 50 | City |
| Holly Ridge | 2 | 6,289 | 4,248 | 6.45% | 1,430 | 4 | Town |
| Swansboro | 3 | 4,273 | 3,754 | 2.37% | 1,912 | 2 | Town |
| Richlands | 4 | 2,523 | 2,291 | 1.53% | 1,245 | 2 | Town |
| North Topsail Beach | 5 | 1,114 | 1,010 | 1.55% | 179 | 6 | Town |
| Topsail Beach | 6 | 511 | 466 | 1.59% | 116 | 4 | Town |
Jacksonville is the largest city in Onslow County, with a population of 72,606.
Topsail Beach is the smallest city in Onslow County, with a population of 511.
There are 6 cities in Onslow County, North Carolina.