9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Gulfport | 1 | 75,056 | 72,880 | 0.58% | 1,349 | 56 | City |
| Biloxi | 2 | 47,823 | 49,428 | -0.67% | 1,114 | 43 | City |
| Long Beach | 3 | 17,318 | 16,810 | 0.59% | 1,691 | 10 | City |
| D'Iberville | 4 | 13,569 | 12,716 | 1.27% | 1,285 | 11 | City |
| St. Martin | 5 | 7,871 | 8,211 | 0.11% | 1,835 | 4 | CDP |
| Pass Christian | 6 | 6,599 | 5,749 | 2.64% | 801 | 8 | City |
| Latimer | 7 | 6,525 | 6,148 | 0.45% | 401 | 16 | CDP |
| Lyman | 8 | 1,481 | 2,303 | 0.95% | 191 | 8 | CDP |
| Saucier | 9 | 1,163 | 1,245 | -1.02% | 168 | 7 | CDP |
Gulfport is the largest city in Harrison County, with a population of 75,056.
Saucier is the smallest city in Harrison County, with a population of 1,163.
There are 9 cities in Harrison County, Mississippi.