Fullerton
- County:
- Orange County
- County Seat:
- No
- Area (mi²):
- 22.42
- State:
- California
Fullerton is a city located in Orange County, California. Fullerton has a 2026 population of 140,054. Fullerton is currently declining at a rate of -0.06% annually and its population has decreased by -2.33% since the most recent census, which recorded a population of 143,398 in 2020.