Sebastien Vachon-Desjardins, from Quebec, Canada, has agreed to plead guilty in a Florida court.
The 34-year-old was affiliated to the NetWalker ransomware crew, which has attacked companies, municipalities, schools and universities.
When he was arrested, police discovered he was in possession of $27m (£22.2m) in Bitcoin.He pleaded guilty to carrying out multiple ransomware attacks from his apartment in Canada.
Police seized dozens of computers and storage devices worth approximately C$35m ($27m, £22m) and C$790,000 in cash from his house. NetWalker hackers extorted $1.14m from a US university and is believed to have contributed to the death of a patient.