Cover Page - shares	6 Months Ended
	Mar. 31, 2023	May 02, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	1-39093
Entity Registrant Name	BellRing Brands, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	87-3296749
Entity Address, Address Line One	2503 S. Hanley Road
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63144
City Area Code	314
Local Phone Number	644-7600
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	BRBR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		132,802,631
Entity Central Index Key	0001772016
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Amendment Flag	false