31 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lebanon | 1 | 26,374 | 26,783 | -0.31% | 6,329 | 4 | City |
| Richland | 2 | 14,382 | 13,829 | 0.57% | 696 | 21 | Township |
| North Lebanon | 3 | 12,314 | 12,049 | 0.74% | 735 | 17 | Township |
| Richland | 4 | 11,956 | 12,234 | -0.4% | 578 | 21 | Township |
| Richland | 5 | 11,892 | 11,925 | 0.47% | 813 | 15 | Township |
| South Lebanon | 6 | 10,708 | 10,439 | 0.7% | 494 | 22 | Township |
| North Cornwall | 7 | 9,504 | 8,484 | 0.41% | 1,001 | 9 | Township |
| North Londonderry | 8 | 9,099 | 8,915 | 0.73% | 847 | 11 | Township |
| South Londonderry | 9 | 9,031 | 8,786 | 1.23% | 371 | 24 | Township |
| Palmyra | 10 | 7,713 | 7,822 | -0.28% | 4,011 | 2 | Borough |
| Swatara | 11 | 5,065 | 5,058 | 0.3% | 235 | 22 | Township |
| Annville | 12 | 5,045 | 4,758 | 0.5% | 3,110 | 2 | Township |
| Cornwall | 13 | 4,673 | 4,607 | 0.28% | 482 | 10 | Borough |
| Millcreek | 14 | 4,462 | 4,367 | 0.7% | 218 | 20 | Township |
| Heidelberg | 15 | 4,126 | 4,100 | 0.98% | 170 | 24 | Township |
| South Annville | 16 | 3,505 | 3,439 | 0.72% | 180 | 19 | Township |
| Palmyra | 17 | 3,412 | 3,211 | 1.1% | 100 | 34 | Township |
| Myerstown | 18 | 3,152 | 3,106 | 0.29% | 3,682 | 1 | Borough |
| Union | 19 | 2,914 | 2,933 | 0.14% | 98 | 30 | Township |
| East Hanover | 20 | 2,711 | 2,660 | 0.71% | 84 | 32 | Township |
| North Annville | 21 | 2,312 | 2,278 | 0.57% | 134 | 17 | Township |
| West Cornwall | 22 | 2,047 | 2,016 | 0.59% | 237 | 9 | Township |
| Cleona | 23 | 2,046 | 2,015 | 0.29% | 2,453 | 1 | Borough |
| Jonestown | 24 | 1,659 | 1,632 | 0.3% | 2,617 | 1 | Borough |
| Richland | 25 | 1,518 | 1,492 | 0.33% | 1,096 | 1 | Borough |
| Palmyra | 26 | 1,253 | 1,243 | -0.08% | 79 | 16 | Township |
| Richland | 27 | 766 | 774 | 0.26% | 34 | 22 | Township |
| Lebanon | 28 | 703 | 679 | 0.86% | 19 | 37 | Township |
| Richland | 29 | 475 | 469 | -0.42% | 32 | 15 | Township |
| Mount Gretna | 30 | 191 | 189 | 0% | 1,326 | 0 | Borough |
| Cold Spring | 31 | 62 | 59 | 3.33% | 2 | 25 | Township |
Lebanon is the largest city in Lebanon County, with a population of 26,374.
Cold Spring is the smallest city in Lebanon County, with a population of 62.
There are 31 cities in Lebanon County, Pennsylvania.