Babar Ahmad, 39, entered the plea in New Haven, Conn., although the federal judge in the case did not immediately say whether or not it would be accepted, the New Haven Register said.
Ahmad was charged with providing material support for terrorism by running a roster of jihadist-oriented Web sites from 1997-2002 that solicited funds for the Taliban as well as the conflicts in Bosnia and Chechnya.
Ahmad was charged in Connecticut because he used a Web-hosting company that purchased server and bandwidth capacity from a firm in Trumbull.
By pleading guilt, Ahmad presumably avoided exposure to as much as 30 years in prison had he been convicted in a trial, the Register said. Prosecutors agreed to drop several counts in exchange for his guilty plea.
Ahmad was tentatively scheduled for sentencing in March. His co-defendant, Syed Talha Ahsan, was also expected to enter a guilty plea late Tuesday.