| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ontario | 1 | 12,014 | 11,771 | 0.48% | 2,007 | 6 | City |
| Nyssa | 2 | 3,272 | 3,212 | 0.46% | 2,111 | 2 | City |
| Vale | 3 | 2,094 | 1,904 | 1.9% | 1,801 | 1 | City |
| Adrian | 4 | 162 | 157 | 0.62% | 664 | 0 | City |
| Jordan Valley | 5 | 143 | 138 | 0.7% | 69 | 2 | City |
Ontario is the largest city in Malheur County, with a population of 12,014.
Jordan Valley is the smallest city in Malheur County, with a population of 143.
There are 5 cities in Malheur County, Oregon.