| Cover | Mar. 01, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 1, 2022 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 001-38869 |
| Entity Registrant Name | HOOKIPA PHARMA INC. |
| Entity Central Index Key | 0001760542 |
| Entity Tax Identification Number | 81-5395687 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 350 Fifth Avenue, 72nd Floor |
| Entity Address, Address Line Two | Suite 7240 |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10118 |
| City Area Code | +43 |
| Local Phone Number | 1 890 63 60 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, $0.0001 |
| Trading Symbol | HOOK |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | true |
