| Document and Entity Information | Jan. 20, 2025 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jan. 20, 2025 |
| Entity Registrant Name | BLACKROCK MUNIVEST FUND, INC. |
| Entity Incorporation State Country Code | MD |
| Entity File Number | 811-05611 |
| Entity Tax Identification Number | 22-2919170 |
| Entity Address Address Line 1 | 50 Hudson Yards |
| Entity Address City Or Town | New York |
| Entity Address State Or Province | NY |
| Entity Address Postal Zip Code | 10001 |
| City Area Code | 212 |
| Local Phone Number | 810-5300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Central Index Key | 0000835948 |
| Amendment Flag | false |
