Chiesa, 30, was scheduled to fight at UFC 223 on April 7 in Brooklyn but was forced to withdraw when he suffered minor injuries during McGregor's attack, days before the fight. McGregor was captured on camera throwing a dolly into a bus that was carrying UFC fighters at Barclays Center.
The lawsuit, which was filed on Monday in Brooklyn and was first reported by TMZ, alleges Chiesa suffered "serious personal, economic, and other injury," as well as "severe emotional distress, mental trauma, and/or bodily harm." It accuses McGregor of negligence, assault, battery and infliction of emotional distress.
In addition to McGregor, Chiesa has listed Barclays Center as a defendant, alleging the facility failed to take "proper security measures to protect the plaintiff and other patrons."
The lawsuit does not specify an amount sought by Chiesa but is seeking relief for compensation lost, including "lost opportunities." Chiesa has stated he believes the incident directly robbed him of a UFC title shot, as the UFC required a last-second replacement for a lightweight title fight at UFC 223 that Chiesa wasn't available for.
McGregor, 30, moved past a criminal case regarding the incident in July, when he agreed to a plea deal with the Brooklyn District Attorney's office. McGregor pleaded guilty to a single violation of disorderly conduct, which allowed him to avoid a criminal record. He is scheduled to return to the Octagon at UFC 229 on Oct. 6.
Chiesa (14-4) recovered from facial lacerations suffered in the attack and fought Anthony Pettis at UFC 226 on July 7 in Las Vegas.