9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Centralia | 1 | 19,227 | 18,397 | 0.87% | 2,462 | 8 | City |
| Chehalis | 2 | 7,776 | 7,479 | 0.76% | 1,339 | 6 | City |
| Winlock | 3 | 2,685 | 1,834 | 6.76% | 794 | 3 | City |
| Napavine | 4 | 2,217 | 1,905 | 2.88% | 767 | 3 | City |
| Morton | 5 | 1,101 | 1,040 | 1.1% | 1,341 | 1 | City |
| Mossyrock | 6 | 810 | 773 | 0.87% | 1,177 | 1 | City |
| Toledo | 7 | 799 | 636 | 4.17% | 1,198 | 1 | City |
| Vader | 8 | 707 | 620 | 2.46% | 761 | 1 | City |
| Pe Ell | 9 | 676 | 648 | 0.75% | 1,144 | 1 | Town |
Centralia is the largest city in Lewis County, with a population of 19,227.
Pe Ell is the smallest city in Lewis County, with a population of 676.
There are 9 cities in Lewis County, Washington.