6 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Jacksonville | 1 | 69,625 | 73,270 | -0.86% | 1,395 | 50 | City |
| Holly Ridge | 2 | 6,527 | 4,243 | 6.2% | 1,484 | 4 | Town |
| Swansboro | 3 | 4,367 | 3,760 | 2.37% | 1,954 | 2 | Town |
| Richlands | 4 | 2,521 | 2,296 | 1.53% | 1,244 | 2 | Town |
| North Topsail Beach | 5 | 1,118 | 1,007 | 1.73% | 180 | 6 | Town |
| Topsail Beach | 6 | 516 | 467 | 1.57% | 118 | 4 | Town |
Jacksonville is the largest city in Onslow County, with a population of 69,625.
Topsail Beach is the smallest city in Onslow County, with a population of 516.
There are 6 cities in Onslow County, North Carolina.