Smith, 25, confessed he first started abusing drugs and alcohol when he was 19, but his addictions spiraled out of control a few years later when someone he cared deeply about got sick, TMZ reported.
The musician said he checked into a treatment center last fall and is now focused on staying clean and sober.
"My goal in releasing this is to try and relate to anyone who has experienced addiction personally or with a loved one, and to be honest with everyone else," Smith wrote in the blog posting this week.
"You can recover!! So, please seek help if you're suffering personally, and urge anyone you know to get help if they are suffering. It gets better one day at a time."