| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Upper Darby | 1 | 85,405 | 85,583 | -0.06% | 10,914 | 8 | Township |
| Chester | 2 | 34,289 | 32,699 | 0.86% | 7,095 | 5 | City |
| Radnor | 3 | 32,080 | 33,226 | -2.58% | 2,329 | 14 | Township |
| Ridley | 4 | 30,945 | 30,953 | -0.04% | 6,050 | 5 | Township |
| Springfield | 5 | 25,025 | 25,048 | -0.06% | 3,959 | 6 | Township |
| Marple | 6 | 24,340 | 24,215 | 0.07% | 2,386 | 10 | Township |
| Springfield | 7 | 21,000 | 20,804 | -0.14% | 3,121 | 7 | Township |
| Upper Chichester | 8 | 16,895 | 16,876 | -0.04% | 2,526 | 7 | Township |
| Aston | 9 | 16,755 | 16,794 | -0.03% | 2,869 | 6 | Township |
| Nether Providence | 10 | 14,458 | 14,399 | -0.07% | 3,067 | 5 | Township |
| Yeadon | 11 | 12,393 | 12,035 | 0.59% | 7,770 | 2 | Borough |
| Lansdowne | 12 | 11,157 | 11,084 | 0.14% | 9,447 | 1 | Borough |
| Upper Providence | 13 | 10,858 | 10,850 | -0.03% | 1,939 | 6 | Township |
| Darby | 14 | 10,663 | 10,686 | -0.03% | 12,664 | 1 | Borough |
| Darby | 15 | 9,200 | 9,211 | -0.07% | 6,497 | 1 | Township |
| Collingdale | 16 | 8,899 | 8,898 | 0.01% | 10,241 | 1 | Borough |
| Brookhaven | 17 | 8,379 | 8,296 | 0.2% | 4,906 | 2 | Borough |
| Ridley Park | 18 | 7,256 | 7,254 | 0.01% | 6,725 | 1 | Borough |
| Glenolden | 19 | 7,216 | 7,221 | -0.01% | 7,401 | 1 | Borough |
| Thornbury | 20 | 6,965 | 6,895 | 0% | 754 | 9 | Township |
| Clifton Heights | 21 | 6,834 | 6,845 | -0.01% | 10,848 | 1 | Borough |
| Folcroft | 22 | 6,779 | 6,788 | -0.01% | 5,445 | 1 | Borough |
| Swarthmore | 23 | 6,569 | 6,531 | 0.12% | 4,692 | 1 | Borough |
| Prospect Park | 24 | 6,407 | 6,420 | -0.03% | 8,753 | 1 | Borough |
| Springfield | 25 | 6,220 | 6,030 | 0.55% | 236 | 26 | Township |
| Sharon Hill | 26 | 5,993 | 6,007 | -0.03% | 7,763 | 1 | Borough |
| Media | 27 | 5,926 | 5,889 | 0.1% | 7,767 | 1 | Borough |
| Norwood | 28 | 5,926 | 5,935 | -0.02% | 7,617 | 1 | Borough |
| Wayne | 29 | 5,412 | 5,201 | 0.5% | 154 | 35 | Township |
| Springfield | 30 | 5,264 | 5,174 | 0.34% | 172 | 31 | Township |
| Edgmont | 31 | 4,718 | 4,296 | 0.25% | 486 | 10 | Township |
| Aldan | 32 | 4,252 | 4,255 | -0.02% | 7,122 | 1 | Borough |
| Chester | 33 | 4,066 | 4,068 | -0.05% | 2,847 | 1 | Township |
| Chadds Ford | 34 | 4,000 | 3,973 | 0.2% | 462 | 9 | Township |
| Tinicum | 35 | 3,983 | 3,980 | -0.05% | 693 | 6 | Township |
| Lower Chichester | 36 | 3,393 | 3,401 | -0.03% | 3,162 | 1 | Township |
| Chester Heights | 37 | 3,221 | 2,914 | 1.19% | 1,455 | 2 | Borough |
| Upland | 38 | 3,048 | 3,053 | -0.03% | 4,696 | 1 | Borough |
| Springfield | 39 | 2,994 | 3,073 | -0.27% | 80 | 37 | Township |
| Morton | 40 | 2,769 | 2,764 | 0.04% | 7,735 | 0 | Borough |
| East Lansdowne | 41 | 2,702 | 2,710 | -0.04% | 13,117 | 0 | Borough |
| Springfield | 42 | 2,617 | 2,739 | -0.65% | 44 | 59 | Township |
| Colwyn | 43 | 2,464 | 2,470 | -0.04% | 9,550 | 0 | Borough |
| Marcus Hook | 44 | 2,447 | 2,454 | -0.04% | 2,208 | 1 | Borough |
| Eddystone | 45 | 2,446 | 2,455 | -0.08% | 2,458 | 1 | Borough |
| Wayne | 46 | 2,399 | 2,469 | -0.21% | 149 | 16 | Township |
| Wayne | 47 | 2,369 | 2,352 | 0.25% | 49 | 49 | Township |
| Parkside | 48 | 2,319 | 2,325 | -0.04% | 11,257 | 0 | Borough |
| Trainer | 49 | 1,971 | 1,973 | -0.05% | 1,865 | 1 | Borough |
| Springfield | 50 | 1,813 | 1,851 | -0.49% | 66 | 27 | Township |
| Wayne | 51 | 1,492 | 1,538 | -0.33% | 39 | 38 | Township |
| Wayne | 52 | 1,462 | 1,452 | 0.27% | 66 | 22 | Township |
| Wayne | 53 | 1,402 | 1,399 | 0.21% | 40 | 35 | Township |
| Wayne | 54 | 1,304 | 1,268 | 0.38% | 94 | 14 | Township |
| Wayne | 55 | 1,259 | 1,302 | -0.24% | 28 | 45 | Township |
| Millbourne | 56 | 1,209 | 1,213 | -0.08% | 16,338 | 0 | Borough |
| Springfield | 57 | 1,124 | 1,147 | -0.35% | 27 | 41 | Township |
| Rose Valley | 58 | 1,017 | 1,017 | 0% | 1,389 | 1 | Borough |
| Wayne | 59 | 1,009 | 1,025 | 0% | 26 | 39 | Township |
| Rutledge | 60 | 778 | 780 | -0.13% | 5,441 | 0 | Borough |
| Springfield | 61 | 678 | 695 | -0.44% | 25 | 28 | Township |
Upper Darby is the largest city in Delaware County, with a population of 85,405.
Springfield is the smallest city in Delaware County, with a population of 678.
There are 61 cities in Delaware County, Pennsylvania.