| 90 | King Heights Academy | Thornhill | Online/Site Based | IB Schools of Ontario | Visit |
| 190 | As-Sadiq Islamic | Thornhill | Site based only | No Association Membership | Visit |
| 245 | C. Lawrence Academy | Thornhill | Online Only | No Association Membership | — |
| 275 | Canada Online School | Thornhill | Online Only | No Association Membership | Visit |
| 292 | Canaway High School | Thornhill | Online Only | No Association Membership | Visit |
| 420 | Halley International Academy | Thornhill | Online/Site Based | No Association Membership | Visit |
| 483 | Kayla's Children Centre | Thornhill | Site based only | No Association Membership | Visit |
| 484 | Kayla's Children Centre (High School) | Thornhill | Site based only | No Association Membership | Visit |
| 560 | Mesivta Thornhill | Thornhill | Site based only | No Association Membership | — |
| 561 | Metro International Secondary Academy | THORNHILL | Online/Site Based | No Association Membership | Visit |
| 568 | Mindview Academy | Thornhill | Online/Site Based | No Association Membership | Visit |
| 583 | Ner Israel Yeshiva | Thornhill | Site based only | No Association Membership | — |
| 628 | Ontario Academy of International Education | Thornhill | Online Only | No Association Membership | Visit |
| 713 | Sharp Eagles | Thornhill | Site based only | No Association Membership | Visit |
| 771 | Torah High - Thornhill | Thornhill | Site based only | No Association Membership | Visit |
| 795 | Toronto Waldorf School | Thornhill | Site based only | Other | Visit |
| 809 | UMCA Rich Tree Academy | Thornhill | Online/Site Based | No Association Membership | Visit |
| 823 | UVA School | Thornhill | Online Only | No Association Membership | Visit |