Published: 2017-03-15 12:10:59 BdST
Affleck, 44, said on his Facebook page that his treatment was the "first of many steps" toward his recovery and specifically thanked his "co-parent," wife Jennifer Garner, whom he separated from in 2015.
"I have completed treatment for alcohol addiction; something I've dealt with in the past and will continue to confront," the "Batman" actor wrote.
"I want my kids to know there is no shame in getting help when you need it, and to be a source of strength for anyone out there who needs help but is afraid to take the first step," he added.
Hollywood A-list couple Affleck and Garner, who have three children together, announced plans to divorce in July 2015 after 10 years of marriage.
Affleck, who has won two Oscars for his writing and producing work, will next be seen reprising the titular superhero role in "The Batman" movie.