| Document and Entity Information | Dec. 10, 2021 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001856589 |
| Document Type | 8-K |
| Document Period End Date | Dec. 10, 2021 |
| Entity Registrant Name | M3-BRIGADE ACQUISITION III CORP. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-40946 |
| Entity Tax Identification Number | 86-3185502 |
| Entity Address, Address Line One | 1700 Broadway |
| Entity Address, Address Line Two | 19th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10019 |
| City Area Code | (212) |
| Local Phone Number | 202-2200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Units Each Consisting Of One Share Of Class A Common Stock And One Third Of One Redeemable Public Warrant 2 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Units, each consisting of one share of Class A common stock and one-third of one redeemable public warrant |
| Trading Symbol | MBSC.U |
| Security Exchange Name | NYSE |
| Common Class A [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Class A common stock, par value $0.0001 per share |
| Trading Symbol | MBSC |
| Security Exchange Name | NYSE |
| Public Warrants Each Whole Public Warrant Exercisable For One Share Of Class A Common Stock At An Exercise Price Of 11.50 Per Share 1 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Public warrants, each whole public warrant exercisable for one share of Class A common stock at an exercise price of $11.50 per share |
| Trading Symbol | MBSC WS |
| Security Exchange Name | NYSE |
