Khalid Ali-M Aldawsari entered his plea at his arraignment before U.S. Magistrate Judge Nancy Koenig at the federal courthouse Monday in Lubbock, Texas. Koenig set a May 2 trial date.
If convicted of attempted use of a weapon of mass destruction, he faces up to life in prison.
Court documents allege he hatched plans to attack various U.S. targets, including New York City and former President George W. Bush's Dallas home.
Aldawsari was arrested Feb. 23. Court records indicate authorities traced his online purchases, discovered extremist online posts he made and secretly searched his apartment, computer and email accounts, and read his diary.
Prosecutors allege Aldawsari had secretly planned for years to launch a terrorist attack. He described in his journal plans to travel to New York City, place bombs in rental cars for remote detonation, and leave the vehicles in different places during rush hour, according to court documents.
He had also researched a network of online street cameras that deliver real-time images of New York streets, prosecutors said.