24 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bellingham | 1 | 96,857 | 91,476 | 1.04% | 3,435 | 28 | City |
| Bellingham | 2 | 96,857 | 91,870 | 1.04% | 3,435 | 28 | City |
| Ferndale | 3 | 17,096 | 15,084 | 2.33% | 2,433 | 7 | City |
| Ferndale | 4 | 17,096 | 15,146 | 2.33% | 2,433 | 7 | City |
| Lynden | 5 | 17,027 | 15,748 | 1.45% | 3,133 | 5 | City |
| Lynden | 6 | 17,027 | 15,806 | 1.45% | 3,133 | 5 | City |
| Birch Bay | 7 | 11,824 | 9,917 | 1.96% | 692 | 17 | CDP |
| Blaine | 8 | 6,488 | 5,885 | 1.84% | 1,161 | 6 | City |
| Blaine | 9 | 6,488 | 5,901 | 1.84% | 1,161 | 6 | City |
| Everson | 10 | 3,223 | 2,940 | 1.7% | 2,159 | 1 | City |
| Everson | 11 | 3,223 | 2,950 | 1.7% | 2,159 | 1 | City |
| Marietta-Alderwood | 12 | 3,154 | 3,463 | -1.56% | 542 | 6 | CDP |
| Peaceful Valley | 13 | 2,563 | 3,187 | -1.95% | 1,023 | 3 | CDP |
| Nooksack | 14 | 1,719 | 1,490 | 2.63% | 1,978 | 1 | City |
| Nooksack | 15 | 1,719 | 1,499 | 2.63% | 1,978 | 1 | City |
| Sumas | 16 | 1,702 | 1,584 | 1.13% | 1,160 | 1 | City |
| Sumas | 17 | 1,702 | 1,607 | 1.13% | 1,160 | 1 | City |
| Point Roberts | 18 | 1,233 | 1,100 | -0.4% | 252 | 5 | CDP |
| Kendall | 19 | 1,151 | 884 | 5.89% | 419 | 3 | CDP |
| Deming | 20 | 446 | 174 | 1.59% | 162 | 3 | CDP |
| Custer | 21 | 285 | 298 | -1.72% | 127 | 2 | CDP |
| Glacier | 22 | 248 | 142 | 0.81% | 148 | 2 | CDP |
| Maple Falls | 23 | 208 | 226 | -3.7% | 97 | 2 | CDP |
| Acme | 24 | 80 | 123 | -12.09% | 53 | 1 | CDP |
Bellingham is the largest city in Whatcom County, with a population of 96,857.
Acme is the smallest city in Whatcom County, with a population of 80.
There are 24 cities in Whatcom County, Washington.