| Cover | Nov. 03, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 3, 2021 |
| Entity Registrant Name | KnowBe4, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-40351 |
| Entity Tax Identification Number | 36-4827930 |
| Entity Address, Address Line One | 33 N. Garden Avenue |
| Entity Address, City or Town | Clearwater |
| Entity Address, State or Province | FL |
| Entity Address, Postal Zip Code | 33755 |
| City Area Code | 855 |
| Local Phone Number | 566-9234 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Stock, par value $0.00001 per share |
| Trading Symbol | KNBE |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity Central Index Key | 0001664998 |
| Amendment Flag | false |
