Sayfullo Saipov could face death penalty if found guilty of most serious charges.
Eight people were killed and a dozen others injured when Sayfullo Saipov allegedly plowed through a bike path in lower Manhattan using a rented truck.
He faces eight counts of murder in aid of racketeering and one count of violently using a motor vehicle resulting in death. All nine charges carry the possibility of the death penalty or life imprisonment, though it is unclear if prosecutors will seek the death penalty.
He also faces 12 charges of attempted murder and one charge of providing and attempting to provide material support to a foreign terrorist organization.
Saipov's lawyer pleaded not guilty on his behalf, according to media reports.
Saipov was immediately taken into custody after the deadly Halloween rampage. He was shot by police after striking a school bus and transferred to a local hospital where he was interviewed after waiving his Miranda Rights, or the right to remain silent after being detained, according to authorities.
During the interrogation, Saipov allegedly requested a Daesh flag be hung in his hospital room while he was recovering from wounds sustained during his arrest, telling officials he felt good about what he had done.
Saipov allegedly admitted to planning an attack about a year ago and decided to use the truck to carry out the attack two months prior.
He entered the U.S. from Uzbekistan in 2010 on a diversity lottery visa, a program President Donald Trump has consistently derided following the attack.
Saipov will next appear in court on Jan. 23.