| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fayette | 1 | 3,350 | 3,335 | 0.39% | 85 | 40 | Township |
| Fermanagh | 2 | 2,851 | 2,869 | -0.35% | 89 | 32 | Township |
| Walker | 3 | 2,776 | 2,782 | -0.5% | 96 | 29 | Township |
| Mifflin | 4 | 2,377 | 2,259 | 0.51% | 124 | 19 | Township |
| Monroe | 5 | 2,026 | 2,043 | -0.15% | 102 | 20 | Township |
| Delaware | 6 | 1,618 | 1,622 | -0.25% | 55 | 30 | Township |
| Mifflin | 7 | 1,070 | 1,089 | -0.65% | 39 | 28 | Township |
| Turbett | 8 | 969 | 978 | 0% | 59 | 16 | Township |
| Mifflintown | 9 | 815 | 839 | -0.49% | 5,821 | 0 | Borough |
| Mifflin | 10 | 812 | 818 | -0.25% | 52 | 15 | Township |
| Spruce Hill | 11 | 800 | 787 | 0.88% | 37 | 22 | Township |
| Port Royal | 12 | 794 | 814 | -0.38% | 1,319 | 1 | Borough |
| Beale | 13 | 783 | 770 | 0% | 36 | 22 | Township |
| Thompsontown | 14 | 631 | 620 | 0.48% | 1,936 | 0 | Borough |
| Lack | 15 | 622 | 636 | -0.48% | 11 | 57 | Township |
| Greenwood | 16 | 536 | 530 | -0.56% | 28 | 19 | Township |
| Mifflin | 17 | 512 | 528 | -0.58% | 2,943 | 0 | Borough |
Fayette is the largest city in Juniata County, with a population of 3,350.
Mifflin is the smallest city in Juniata County, with a population of 512.
There are 17 cities in Juniata County, Pennsylvania.