A Nigerian influencer known as Hushpuppi pleaded guilty in a US court to money laundering.
Ramon Abbas could face 20 years in prison after admitting the charge in a California court on Thursday.
The 37-year-old was arrested in Dubai last year in a highly publicised raid on his luxury apartment at a five-star hotel.
Court documents said Abbas's crimes cost victims almost $24 million in total. Prosecutors previously alleged he was responsible for scams valued at hundreds of millions of dollars.
In one scheme, he tried to steal more than $1.1 million from someone who wanted to fund a new children's school in Qatar.
Court records unsealed this week show he pleaded guilty to this charge on April 20, 2021.
He will need to "pay full restitution to the victims" if he is to be released.
Commenting on the Qatar scam in a statement, acting US attorney Tracy Wilkinson said Abbas and his accomplices posed as bank officials and created a bogus website to fake the financing of the school.
The gang also bribed a foreign official to keep the elaborate pretence going after the victim was tipped off.
Rolls-Royces and purple bathrobes
The court heard of Abbas's extravagant lifestyle – he lived in the residence of the Palazzo Versace on Dubai Creek and owned a fleet of luxury cars.
His Instagram account – last updated shortly before his arrest 59 weeks ago – had 2.5 million followers and his final post was about collecting a new Rolls-Royce Cullinan. Other pictures show him stepping out of a helicopter at Dubai's Atlantis The Palm resort.
He had fans believe he was a highly successful businessman who made it big in Dubai and the Middle East. He had a penchant for loud shirts, private jet travel, purple bathrobes and he lived and spent extravagantly.
Kristi Johnson, acting director of the FBI's Los Angeles office, told BBC News that Abbas one of the "most high-profile money launderers in the world", acting in the open rather than the shadows.
Almost $41 million in cash and 13 cars valued at about $6.8 million were seized, as were phone and computer evidence containing more than 100,000 fraudulent files. In addition, the email addresses of nearly two million possible victims were found, Dubai Police said at the time.