We got Ronnie at Avra in Beverly Hills on Thursday and he told our photog he's 4 months sober and planning to return to 'Jersey Shore' by the end of the 5th season.

It's welcome news for 'Jersey Shore' fans who've been missing Ron, and for him ... because it sounds like he's in a better place in his life.

As we reported ... Ronnie announced back in May he was stepping away from the show that made him famous as a result of mental health issues.

Ronnie's departure came in the wake of his domestic violence arrest, with Ron and MTV honchos agreeing he needed some time away from the cameras to seek treatment for issues he felt he was ignoring.

Ron says he's learned from his mountain of legal issues over the years ... and he says he's become a better father and fiancé.

As you know ... Ronnie got engaged to Saffire Matos despite allegedly attacking her and getting arrested. He ended up dodging criminal charges in the case.

Ronnie also tells us who is getting wedding invites and who is getting snubbed ... and it sounds like his ex, Jenn Harley, doesn't need to sit by the mailbox.