| North Lakeland Discovery CenterEIN 39-1852858 | Environment | WI | $872,690Small | 82.53 |
| North Penn United WayEIN 23-1576820 | Community Development | PA | $1,633,548Small | 83.11 |
| North Shore Animal League AmericaEIN 11-1666852 | Animals | NY | $41,531,218Large | 83.38 |
| Northampton Survival CenterEIN 04-2774166 | Human Services | MA | $2,120,033Small | 85.59 |
| Northeast Indiana Public RadioEIN 35-1514924 | Arts, Culture, Humanities | IN | $1,183,397Small | 82.20 |
| Northern Clay CenterEIN 41-1616650 | Arts, Culture, Humanities | MN | $1,760,777Small | 89.54 |
| Northern Stage CompanyEIN 04-3387268 | Arts, Culture, Humanities | VT | $3,628,374Mid-sized | 82.30 |
| Northwest Arkansas Food BankEIN 71-0680830 | Human Services | AR | $19,790,770Large | 83.35 |
| Northwest FolklifeEIN 91-1311548 | Arts, Culture, Humanities | WA | $1,496,363Small | 83.07 |
| Northwest Montana United WayEIN 81-0304856 | Community Development | MT | $747,976Small | 81.02 |
| Norton Museum of ArtEIN 59-0624432 | Arts, Culture, Humanities | FL | $13,115,172Mid-sized | 80.09 |
| Noyes Home for ChildrenEIN 44-0563788 | Human Services | MO | $2,369,119Small | 80.79 |
| NPH USAEIN 65-1229309 | Human Services | IL | $18,458,495Large | 87.23 |
| NPREIN 52-0907625 | Arts, Culture, Humanities | DC | $222,910,067Large | 84.25 |
| NW Children's FoundationEIN 91-1314318 | Human Services | WA | $1,390,355Small | 86.10 |
| Oakland East Bay SymphonyEIN 94-3081554 | Arts, Culture, Humanities | CA | $2,813,517Small | 86.89 |
| Ocean InstituteEIN 33-0203488 | Education | CA | $6,496,221Mid-sized | 86.98 |
| Ohio City IncorporatedEIN 34-1372076 | Community Development | OH | $1,197,417Small | 85.47 |
| Ohio Environmental CouncilEIN 31-0805578 | Environment | OH | $2,085,734Small | 83.94 |
| Ohio United WayEIN 31-0619209 | Community Development | OH | $872,862Small | 83.50 |
| Ohr Torah Stone Colleges and Graduate ProgramsEIN 13-3275531 | Religion | NY | $5,013,619Mid-sized | 81.38 |
| Okizu FoundationEIN 68-0291178 | Health | CA | $2,017,839Small | 86.23 |
| Oklahoma Arts InstituteEIN 73-1021165 | Education | OK | $2,394,342Small | 86.44 |
| Oklahoma Baptist Homes for ChildrenEIN 73-1435473 | Human Services | OK | $13,396,030Mid-sized | 82.36 |
| Oklahoma City Art MuseumEIN 73-0528431 | Arts, Culture, Humanities | OK | $8,417,047Mid-sized | 86.56 |
| Oklahoma City BalletEIN 23-7003520 | Arts, Culture, Humanities | OK | $3,575,680Mid-sized | 80.71 |
| Oklahoma Humane SocietyEIN 20-8446621 | Animals | OK | $3,137,627Small | 89.38 |
| Oklahoma Institute for Child AdvocacyEIN 73-1192768 | Human Services | OK | $894,750Small | 80.87 |
| Olbrich Botanical SocietyEIN 39-1357247 | Environment | WI | $2,874,467Small | 88.26 |
| Old Dominion Athletic FoundationEIN 54-6051933 | Education | VA | $7,930,953Mid-sized | 89.39 |
| Oldways Preservation TrustEIN 04-3031978 | Research and Public Policy | MA | $2,135,083Small | 85.00 |
| Oliver Gospel MissionEIN 57-6027750 | Human Services | SC | $3,388,839Small | 88.44 |
| Omaha Community PlayhouseEIN 47-0399856 | Arts, Culture, Humanities | NE | $4,315,647Mid-sized | 80.52 |
| Omaha Performing ArtsEIN 47-0832480 | Arts, Culture, Humanities | NE | $18,775,491Large | 85.12 |
| Omaha's Henry Doorly ZooEIN 47-0469782 | Animals | NE | $46,482,503Large | 87.05 |
| On PointEIN 68-0533402 | Human Services | TN | $1,327,471Small | 89.10 |
| On The RiseEIN 04-3290689 | Human Services | MA | $1,227,796Small | 89.22 |
| Oncology Nursing Society FoundationEIN 25-1410081 | Health | PA | $1,399,783Small | 88.19 |
| One Child MattersEIN 84-1087689 | International | CO | $16,670,568Large | 85.81 |
| One CollectiveEIN 36-6069820 | Religion | IL | $11,173,031Mid-sized | 83.24 |
| One FamilyEIN 54-2076936 | Human Services | MA | $1,493,655Small | 88.22 |
| One HeartlandEIN 39-1763115 | Health | MN | $1,622,396Small | 85.75 |
| One Million DegreesEIN 42-1710230 | Education | IL | $2,667,285Small | 87.16 |
| One VoiceEIN 95-3900124 | Human Services | CA | $1,716,351Small | 87.68 |
| OneAmericaEIN 20-0384893 | Human and Civil Rights | WA | $3,534,222Mid-sized | 88.68 |
| OneFamilyEIN 11-3585917 | Human Services | NJ | $1,086,033Small | 82.43 |
| OneGoalEIN 56-2369898 | Education | IL | $11,929,410Mid-sized | 85.76 |
| OneVoice MovementEIN 30-0102398 | International | NY | $3,731,582Mid-sized | 88.81 |
| Open BooksEIN 20-4830666 | Education | IL | $2,045,810Small | 84.17 |
| Open Door Mission, HoustonEIN 76-0146890 | Human Services | TX | $2,973,113Small | 80.91 |
| Open Door Mission, OmahaEIN 47-0411375 | Human Services | NE | $29,651,669Large | 89.84 |
| Open Doors USAEIN 23-7275342 | Religion | CA | $23,492,166Large | 87.35 |
| Open HandEIN 58-1816778 | Human Services | GA | $11,503,460Mid-sized | 88.63 |
| Open Your Heart to the Hungry and HomelessEIN 36-3488089 | Human Services | MN | $784,716Small | 89.50 |
| OpenhouseEIN 94-3337955 | Human Services | CA | $1,606,068Small | 89.17 |
| Opera MemphisEIN 62-0785544 | Arts, Culture, Humanities | TN | $1,623,169Small | 83.52 |
| Operation AccessEIN 94-3180356 | Health | CA | $1,466,203Small | 86.33 |
| Operation Blessing InternationalEIN 54-1382657 | International | VA | $272,605,727Large | 82.43 |
| Operation Finally HomeEIN 20-8964096 | Human Services | TX | $6,922,291Mid-sized | 80.85 |
| Operation HomefrontEIN 32-0033325 | Human Services | TX | $48,352,893Large | 89.18 |