31 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lebanon | 1 | 26,292 | 26,783 | -0.31% | 6,310 | 4 | City |
| Richland | 2 | 14,464 | 13,829 | 0.57% | 700 | 21 | Township |
| North Lebanon | 3 | 12,404 | 12,049 | 0.73% | 741 | 17 | Township |
| Richland | 4 | 11,948 | 11,925 | 0.47% | 817 | 15 | Township |
| Richland | 5 | 11,908 | 12,234 | -0.4% | 576 | 21 | Township |
| South Lebanon | 6 | 10,782 | 10,439 | 0.69% | 497 | 22 | Township |
| North Cornwall | 7 | 9,543 | 8,484 | 0.41% | 1,005 | 9 | Township |
| North Londonderry | 8 | 9,165 | 8,915 | 0.73% | 854 | 11 | Township |
| South Londonderry | 9 | 9,141 | 8,786 | 1.22% | 375 | 24 | Township |
| Palmyra | 10 | 7,691 | 7,822 | -0.29% | 3,999 | 2 | Borough |
| Swatara | 11 | 5,080 | 5,058 | 0.3% | 236 | 22 | Township |
| Annville | 12 | 5,070 | 4,758 | 0.5% | 3,126 | 2 | Township |
| Cornwall | 13 | 4,686 | 4,607 | 0.28% | 483 | 10 | Borough |
| Millcreek | 14 | 4,493 | 4,367 | 0.69% | 220 | 20 | Township |
| Heidelberg | 15 | 4,166 | 4,100 | 0.97% | 172 | 24 | Township |
| South Annville | 16 | 3,530 | 3,439 | 0.71% | 181 | 19 | Township |
| Palmyra | 17 | 3,449 | 3,211 | 1.08% | 101 | 34 | Township |
| Myerstown | 18 | 3,161 | 3,106 | 0.29% | 3,693 | 1 | Borough |
| Union | 19 | 2,918 | 2,933 | 0.14% | 98 | 30 | Township |
| East Hanover | 20 | 2,730 | 2,660 | 0.7% | 84 | 32 | Township |
| North Annville | 21 | 2,325 | 2,278 | 0.56% | 135 | 17 | Township |
| West Cornwall | 22 | 2,059 | 2,016 | 0.59% | 238 | 9 | Township |
| Cleona | 23 | 2,052 | 2,015 | 0.29% | 2,460 | 1 | Borough |
| Jonestown | 24 | 1,665 | 1,632 | 0.36% | 2,626 | 1 | Borough |
| Richland | 25 | 1,523 | 1,492 | 0.33% | 1,100 | 1 | Borough |
| Palmyra | 26 | 1,252 | 1,243 | -0.08% | 79 | 16 | Township |
| Richland | 27 | 768 | 774 | 0.26% | 35 | 22 | Township |
| Lebanon | 28 | 709 | 679 | 0.85% | 19 | 37 | Township |
| Richland | 29 | 473 | 469 | -0.42% | 31 | 15 | Township |
| Mount Gretna | 30 | 192 | 189 | 0.52% | 1,333 | 0 | Borough |
| Cold Spring | 31 | 64 | 59 | 3.23% | 3 | 25 | Township |
Lebanon is the largest city in Lebanon County, with a population of 26,292.
Cold Spring is the smallest city in Lebanon County, with a population of 64.
There are 31 cities in Lebanon County, Pennsylvania.