| On the MoveEIN 75-3149095 | Education | CA | $4,571,332Mid-sized | 90.58 |
| One Heart World-WideEIN 20-0443243 | International | CA | $2,298,326Small | 96.66 |
| One VoiceEIN 95-3900124 | Human Services | CA | $1,716,351Small | 87.68 |
| One World Children's FundEIN 77-0479205 | International | CA | $2,242,722Small | 98.23 |
| OneSkyEIN 95-4714047 | International | CA | $6,328,760Mid-sized | 92.63 |
| Open Doors USAEIN 23-7275342 | Religion | CA | $23,492,166Large | 87.35 |
| OpenhouseEIN 94-3337955 | Human Services | CA | $1,606,068Small | 89.17 |
| Opera San JoséEIN 77-0009773 | Arts, Culture, Humanities | CA | $4,434,463Mid-sized | 92.72 |
| Operation AccessEIN 94-3180356 | Health | CA | $1,466,203Small | 86.33 |
| Operation GratitudeEIN 20-0103575 | Human Services | CA | $10,112,056Mid-sized | 92.38 |
| Operation HOPEEIN 95-4378084 | Education | CA | $15,027,756Large | 87.82 |
| Operation USAEIN 95-3504080 | International | CA | $3,338,684Small | 92.92 |
| Opportunity Fund Community Development EIN 31-1719434 | Community Development | CA | $19,078,312Large | 91.49 |
| Orange County CoastkeeperEIN 33-0847892 | Environment | CA | $1,772,988Small | 94.74 |
| Orange County Community FoundationEIN 33-0378778 | Community Development | CA | $64,365,979Large | 94.37 |
| Orange County Museum of ArtEIN 95-1660847 | Arts, Culture, Humanities | CA | $2,605,178Small | 85.08 |
| Orange County Rescue MissionEIN 95-2479552 | Human Services | CA | $16,241,092Large | 91.21 |
| Orange County United WayEIN 33-0047994 | Community Development | CA | $17,947,341Large | 89.73 |
| Orangewood FoundationEIN 95-3616628 | Human Services | CA | $9,272,668Mid-sized | 92.50 |
| Orangutan Foundation InternationalEIN 95-4112467 | Animals | CA | $1,603,050Small | 93.42 |
| Organic Farming Research FoundationEIN 77-0252545 | Research and Public Policy | CA | $871,992Small | 87.24 |
| OUR HOUSE Grief Support CenterEIN 33-0529915 | Human Services | CA | $2,122,838Small | 90.85 |
| Out & Equal Workplace AdvocatesEIN 02-0681855 | Human and Civil Rights | CA | $5,530,425Mid-sized | 89.54 |
| P.S. ARTSEIN 95-3931147 | Education | CA | $3,563,508Mid-sized | 95.95 |
| Pacific Crest Trail AssociationEIN 33-0051202 | Environment | CA | $3,359,863Small | 81.60 |
| Pacific EnvironmentEIN 94-2628924 | Environment | CA | $1,330,701Small | 86.58 |
| Pacific Justice InstituteEIN 91-1823641 | Human and Civil Rights | CA | $2,058,162Small | 80.41 |
| Pacific Marine Mammal CenterEIN 95-3680896 | Animals | CA | $1,876,899Small | 87.87 |
| Pacific Research InstituteEIN 94-2528433 | Research and Public Policy | CA | $6,339,545Mid-sized | 79.47 |
| Pacific SymphonyEIN 95-3635496 | Arts, Culture, Humanities | CA | $20,980,482Large | 82.32 |
| Palm Springs Art MuseumEIN 95-1809576 | Arts, Culture, Humanities | CA | $12,050,122Mid-sized | 78.26 |
| Palo Alto Partners in EducationEIN 77-0186364 | Education | CA | $6,185,868Mid-sized | 88.98 |
| Pancreatic Cancer Action NetworkEIN 33-0841281 | Health | CA | $32,108,869Large | 93.02 |
| Parents Television CouncilEIN 95-4819071 | Human Services | CA | $2,193,488Small | 75.49 |
| Parkinson's Institute and Clinical CenterEIN 94-3061594 | Health | CA | $8,641,345Mid-sized | 75.52 |
| Pasadena Conservatory of MusicEIN 95-3900207 | Arts, Culture, Humanities | CA | $2,985,332Small | 91.23 |
| Pasadena Humane Society & SPCAEIN 95-1643344 | Animals | CA | $10,723,629Mid-sized | 93.24 |
| PAWS/LAEIN 95-4178092 | Animals | CA | $1,224,056Small | 80.63 |
| Pediatric Cancer Research FoundationEIN 95-3772528 | Health | CA | $2,492,062Small | 86.97 |
| Peninsula Education FoundationEIN 95-3498211 | Education | CA | $4,934,154Mid-sized | 93.31 |
| Peninsula Humane Society & SPCAEIN 94-1243665 | Animals | CA | $12,522,099Mid-sized | 80.84 |
| Peninsula Jewish Community CenterEIN 94-3227262 | Human Services | CA | $18,227,062Large | 89.45 |
| Performing Animal Welfare SocietyEIN 94-3005157 | Animals | CA | $3,534,605Mid-sized | 94.64 |
| Pet Adoption FundEIN 95-3842460 | Animals | CA | $549,106Small | 82.91 |
| Pet Orphans of Southern CaliforniaEIN 23-7267769 | Animals | CA | $1,069,131Small | 69.43 |
| Petersen Automotive MuseumEIN 95-4739699 | Arts, Culture, Humanities | CA | $20,476,879Large | 86.62 |
| Pets in NeedEIN 94-6139667 | Animals | CA | $2,138,611Small | 91.81 |
| Pico National NetworkEIN 94-2206497 | Community Development | CA | $16,391,482Large | 89.67 |
| Placer SPCAEIN 94-2607682 | Animals | CA | $2,612,719Small | 90.22 |
| Planned Parenthood California Central CoastEIN 95-2319356 | Health | CA | $15,587,708Large | 86.56 |
| Planned Parenthood Los AngelesEIN 95-2408623 | Health | CA | $60,666,128Large | 85.17 |
| Planned Parenthood Mar MonteEIN 94-1583439 | Health | CA | $94,167,698Large | 88.68 |
| Planned Parenthood of Orange and San Bernardino CountiesEIN 95-6152773 | Health | CA | $50,359,148Large | 91.50 |
| Plant With PurposeEIN 33-0052976 | International | CA | $4,383,009Mid-sized | 89.20 |
| PlayworksEIN 94-3251867 | Education | CA | $42,345,360Large | 86.11 |
| Ploughshares FundEIN 94-2764520 | International | CA | $9,459,257Mid-sized | 92.05 |
| Point Blue Conservation ScienceEIN 94-1594250 | Animals | CA | $12,617,172Mid-sized | 92.38 |
| Point FoundationEIN 84-1582086 | Education | CA | $4,447,216Mid-sized | 90.41 |
| PolicyLinkEIN 94-3297479 | Research and Public Policy | CA | $12,167,006Mid-sized | 88.22 |
| Pollinator PartnershipEIN 94-3283967 | Animals | CA | $1,072,782Small | 84.42 |