Michael Coleman has been cleared of charges that he conspired to commit a terrorist act at Bayside High School's end-of-the-year prom at a hotel at Town Center.
Charges were dropped by prosecutors due to insufficient evidence.
If he had been convicted of the crimes with which he was charged, he could have served at least 20 years and up-to-life in prison.
Coleman is still being held in the Norfolk jail for other criminal charges and faces a Aug. 10 court date in Virginia Beach on them.
Prosecutors have already dropped terrorism-related felony charges against a 17-year-old boy involved in the incident.