The Staten Island native, who made his name in ECW before being inducted into the Indie Wrestling Hall of Fame, was 60.
No cause of death has been confirmed.
Sabu was among the most popular hardcore wrestlers in the business and had a brief run with WWE in the mid-2000s.
News of his death comes weeks after his victory over GCW star and former WWE wrestler Joey Janela on April 18.
Sabu was trained by his uncle, "The Sheik" and was a mainstay in the business for decades, working the indie scene until settling in with ECW and then WWE for a short stint.
The wrestling world took to social media to mourn Sabu's death, including ECW greats Taz and Rob Van Dam, both of whom he had heated rivalries with the hardcore legend.
AEW and the wrestling world mourns the passing of Sabu," the promotion posted on X." From barbed wire battles to unforgettable high-risk moments, Sabu gave everything to professional wrestling."
“I would not have had the career that I have had, and I’ve been blessed to have, if it wasn’t for Sabu. That man got me over, and he didn’t have to get me over, and he did,” Taz said in a video posted on X.
“A great heart and soul. I’m gonna miss him immensely.”
Click here to follow Daily Voice Waynesboro and receive free news updates.