9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Marietta | 1 | 63,914 | 61,051 | 0.9% | 2,719 | 23.51 | City |
| Smyrna | 2 | 56,832 | 56,167 | 0.23% | 3,554 | 15.99 | City |
| Mableton | 3 | 42,780 | 41,647 | 0.89% | 2,095 | 20.42 | CDP |
| Kennesaw | 4 | 35,562 | 33,364 | 1.25% | 3,644 | 9.76 | City |
| Powder Springs | 5 | 20,310 | 16,910 | 3.46% | 2,601 | 7.81 | City |
| Vinings | 6 | 13,750 | 12,546 | 1.99% | 4,399 | 3.13 | CDP |
| Fair Oaks | 7 | 9,961 | 9,447 | 1.17% | 5,103 | 1.95 | CDP |
| Austell | 8 | 8,335 | 7,867 | 1.14% | 1,314 | 6.34 | City |
| Kennesaw State University | 9 | 3,302 | 3,568 | 7.14% | 8,423 | 0.39 | CDP |
Marietta is the largest city in Cobb County, with a population of 63,914.
Kennesaw State University is the smallest city in Cobb County.
There are 9 cities in Cobb County, Georgia.