Cover - shares	9 Months Ended
	Sep. 30, 2025	Oct. 31, 2025
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2025
Document Transition Report	false
Entity File Number	001-42805
Registrant Name	Miami International Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-1482385
Entity Address, Address Line One	7 Roszel Road
Entity Address, Address Line Two	Suite 1A
Entity Address, City or Town	Princeton
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08540
City Area Code	609
Local Phone Number	897-7300
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	MIAX
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		81,435,030
Central Index Key	0001438472
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q3
Amendment Flag	false