| Cover | Jun. 26, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jun. 26, 2024 |
| Entity File Number | 001-40199 |
| Entity Registrant Name | GREENBROOK TMS INC. |
| Entity Central Index Key | 0001735948 |
| Entity Tax Identification Number | 98-1512724 |
| Entity Incorporation, State or Country Code | A6 |
| Entity Address, Address Line One | 890 Yonge Street, 7th Floor |
| Entity Address, City or Town | Toronto |
| Entity Address, Country | CA |
| Entity Address, Postal Zip Code | M4W 3P4 |
| City Area Code | 866 |
| Local Phone Number | 928-6076 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Shares, without par value |
| Trading Symbol | GBNHF |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
