Simi Valley
- County:
- Ventura County
- County Seat:
- No
- Area (mi²):
- 41.542
- State:
- California
Simi Valley is a city located in Ventura County, California. Simi Valley has a 2026 population of 125,778. Simi Valley is currently growing at a rate of 0.4% annually but its population has decreased by -0.45% since the most recent census, which recorded a population of 126,347 in 2020.