| Perigee Fund | Related tax-exempt org | Grantmaking and convening for early childhood and maternal mental health | WA | 830847498 |
| Seattle Foundation | Related tax-exempt org | Serves charitable organizations in the greater seattle AREA | WA | 916013536 |
| Seattle International Foundation | Related tax-exempt org | Grantmaking to ORGS to enhance international philanthropy in PNW | WA | 208350995 |
| TSF Properties | Related tax-exempt org | Receive, hold, & dispose of property donations for seattle foundation | WA | 912016094 |
| TSF Services | Related tax-exempt org | Support grantmaking and administrative activities of seattle foundation | WA | 912008707 |
| IPD Breakthrough Fund | Related tax-exempt org | Grantmaking to nonprofits in the greater puget sound community | WA | 854217292 |
| Edenburt Charitable Fund | Related tax-exempt org | Support the activities of seattle foundation | WA | 854267020 |
| George P Hardgrove Foundation | Related tax-exempt org | Grantmaking to nonprofits in the greater puget sound community | WA | 916061389 |
| SRF Charitable Trust | Related taxable corporation/trust | Manage investments | WA | 916059260 |
| REF Trust FBO Seattle Foundation | Related taxable corporation/trust | Manage investments | WA | 916027079 |
| MEF Trust FBO Seattle Foundation | Related taxable corporation/trust | Manage investments | WA | 916027080 |
| DMH Charitable Trust FBO Seattle Foundation | Related taxable corporation/trust | Manage investments | WA | 916023538 |
| HP Charitable Trust FBO Seattle Foundation | Related taxable corporation/trust | Manage investments | WA | 916023566 |
| AWW Trust FBO Seattle Foundation | Related taxable corporation/trust | Manage investments | WA | 911034032 |
| Charitable Remainder Trust (16) | Related taxable corporation/trust | Manage investments | WA | — |
| Charitable Lead Trust (1) | Related taxable corporation/trust | Manage investments | WA | — |