The news follows rumors Affleck and estranged wife Jennifer Garner had halted their ongoing divorce process, spurring hopes of reconciliation. The couple issued a joint statement in the summer of 2015.
"After much thought and careful consideration, we have made the difficult decision to divorce," the statement read. "We go forward with love and friendship for one another and a commitment to co-parenting our children whose privacy we ask to be respected during this difficult time."
Since that time, both parties have remained mum on the reason for the breakup. Now, it seems 44-year-old Affleck is attempting to clear the air, citing being a good example to his three young kids as the driving force behind rehabilitation.
"I have completed treatment for alcohol addiction; something I've dealt with in the past and will continue to confront," Affleck wrote Tuesday afternoon. "I want to live life to the fullest and be the best father I can be. 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.
"I'm lucky to have the love of my family and friends, including my co-parent, Jen, who has supported me and cared for our kids as I've done the work I set out to do," Affleck continued. "This was the first of many steps being taken towards a positive recovery."
This is Affleck's second public stint in rehab, the first being in 2001.