| Business | Phone |
| Armstrong Center 1265 S Palmetto Ave, Ontario 91762 | (909) 395-2020 |
| Code Enforcement 121 N Plum St, Ontario 91764 | (909) 467-2723 |
| Deanza Community & Teen Center 1405 S Fern Ave, Ontario 91762 | (909) 395-2030 |
| Multi Purpose Building 225 E B St, Ontario 91764 | (909) 988-9841 |
| City Of Ontario 2500 S Archibald Ave, Ontario 91761 | (909) 458-6800 |
| Ontario Building Dept 303 E B St, Ontario 91764 | (909) 395-2023 |
| Ontario Business Licenses 303 E B St, Ontario 91764 | (909) 395-2022 |
| Ontario City Code Enforcement 121 N Plum St, Ontario 91764 | (909) 395-2007 |
| Ontario City Council 303 E B St, Ontario 91764 | (909) 395-2011 |
| Ontario City Fiscal Svc 303 E B St, Ontario 91764 | (909) 395-2026 |
| Ontario Development Agency 303 E B St, Ontario 91764 | (909) 395-2024 |
| Ontario Engineering Dept 303 E B St, Ontario 91764 | (909) 395-2025 |
| Ontario Personnel Dept 303 E B St, Ontario 91764 | (909) 395-2034 |
| Ontario Planning Dept 303 E B St, Ontario 91764 | (909) 395-2036 |
| Ontario Public Svc Agency 1425 S Bon View Ave, Ontario 91761 | (909) 395-2600 |
| Ontario Purchasing Dept 303 E B St, Ontario 91764 | (909) 395-2012 |
| Ontario Risk Management 303 E B St, Ontario 91764 | (909) 395-2041 |
| Ontario Teen Center 1205 N Baker Ave, Ontario 91764 | (909) 395-3679 |