Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | 2024 Pop. | 2020 Pop. | Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Jacksonville | 1 | 72,198 | 74,922 | -0.93% | 1,479 | 48.8 | City |
| Piney Green | 2 | 15,013 | 14,309 | 0.83% | 1,101 | 13.6 | CDP |
| Half Moon | 3 | 8,386 | 8,384 | 0.04% | 1,130 | 7.4 | CDP |
| Holly Ridge | 4 | 5,478 | 4,244 | 5.96% | 1,296 | 4.2 | Town |
| Swansboro | 5 | 4,264 | 3,756 | 3.07% | 1,908 | 2.2 | Town |
| Richlands | 6 | 2,455 | 2,294 | 1.66% | 1,487 | 1.7 | Town |
| Pumpkin Center | 7 | 2,139 | 1,850 | -0.28% | 1,688 | 1.3 | CDP |
| Sneads Ferry | 8 | 2,056 | 2,326 | -2% | 541 | 3.8 | CDP |
| North Topsail Beach | 9 | 1,089 | 1,009 | 1.87% | 175 | 6.2 | Town |
| Topsail Beach | 10 | 507 | 466 | 2.01% | 115 | 4.4 | Town |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
Jacksonville is the largest city in Onslow County.
Topsail Beach is the smallest city in Onslow County.
There are 10 cities in Onslow County, North Carolina.