A U.S. judge who leaked Charlize Theron's adoption news has been banned from the bench for life following an ethics probe.

Arkansas Circuit Judge Mike Maggio was the target of an official investigation into allegations of ethics violations, including claims he disclosed private details of the Hollywood actress' adoption of son Jackson in 2012 on social media.

Maggio, who admitted posting about Theron's adoption case in an online chat forum, has been suspended until the end of the year (14) when he will be officially removed from office.

Officials from the Arkansas Judicial Discipline and Disability Commission, who conducted the investigation, also banned him from serving as a judge for life.

The agreement must be approved by Arkansas' Supreme Court before it is finalised.

Maggio says, "I take full responsibility... I apologise deeply for my lapse in personal judgment and for that, I have no excuse."