The All Elite Wrestling (AEW) star - who appeared as Dean Ambrose for eight years in WWE before his exit in April 2019 - gave his boss Tony Khan permission to make the announcement on social media.
In a statement on Twitter, Khan wrote: "Jon Moxley has allowed me to share with you that he is entering an inpatient alcohol treatment program.
"Jon is a beloved member of the AEW family. We all stand with him and Renee, and all of his family and friends, as he shifts his focus to recovery.
"Jon is making a very brave choice to get help, and we’re embracing his choice and supporting him however we can.
"I’m proud to call Jon a friend, and like many of you, I’m also a fan of Mox and look forward to a time in the future when he is eventually ready to return to the ring.
"Until then, thank you for supporting Jon and respecting his privacy at this time."
Moxley - who welcomed daughter Nora into the world with his wife Renee Paquette in June - had been scheduled to face Orange Cassidy in the semi-finals of the ongoing AEW World Title Eliminator Tournament.
A number of stars have paid tribute to the star on social media, including WWE Hall of Famer Mick Foley.
He wrote: "Wishing Jon the very best. A bold and brave decision - and I know he’ll be back and better than ever. Mox has a heck of a support system, with great fans, and an amazing wife."
AEW's Cash Wheeler added: "More respect than ever for Jon."
His co-star Thunder Rosa tweeted: "We all love you and support you Mox! This is a difficult journey but we are here for you and Renee!"
And AEW commentator Taz said: "I have no doubt that Mox will succeed in his battle. Much respect Jon."