Raynaldo Rivera, 20, has been accused of helping carry out cyber attacks on Sony Pictures last year, and faces up to 15 years in prison if found guilty.
Rivera is said to have aided fellow hacker Cody Kretsinger with the Sony breach, which resulted in the personal details of competition entrants leaking online, costing the company a reported $600,000 (£380,000).
The FBI claim that Rivera helped leak the sensitive information on the internet, and publicised the attack on websites such as Twitter under a variety of pseudonyms, BBC News reports.
Kretsinger, 24, pleased guilty to hacking charges in April. LulzSec leader Hector Xavier Monsegur had been working undercover with the FBI to trace members of the group following his arrest in 2011.
Back in June, UK residents Jake Davis, 19, and Ryan Cleary, 20, pleased guilty to cyber crimes after being exposed as members of LulzSec.