Joseph O'Connor was arrested in the Spanish coastal resort town of Estepona on an international arrest warrant, the U.S. Department of Justice said on Wednesday.
He has been charged in the United States for alleged involvement in a widespread Twitter hack that compromised the accounts of a number of prominent U.S. politicians, celebrities and tech moguls in July 2020.
Prosecutors have also accused O'Connor of breaking into accounts on the social media apps TikTok and Snapchat, and of "cyberstalking a juvenile".
A criminal complaint has been filed in a federal court in the Northern District of California. O'Connor is formally charged with cyberstalking, making extortive and threatening communications, and intentionally accessing a computer without authorisation.
During the high-profile security breach, fake tweets were sent from a number of high-profile social media accounts, urging followers to send them Bitcoin payments.