The 25-year-old broke the news through his Twitter page and is expected to miss the next eight weeks of the season as Stale Solbakken's side look to get back into the top flight
The ex-Portsmouth and Tottenham man has not played for the Black Country side since March, following surgery in December of 2011, and will now sit out the next eight weeks of the season.
|WOLVES TAKE DOWN BLUEBIRDS|
|12/1||Wolves are 12/1 with Bet365 to beat Cardiff 2-1 on Sunday|
Despite the ongoing frustration, O'Hara is keen to see the issue resolved sooner rather than later, and wants to make an impact later in the campaign.
"Sorry to disappoint the fans but am having surgery tomorrow [Wednesday] on my hernia - the first operation didn't seem to work," he told fans through his Twitter account.
"I'm hoping to be fit in around eight weeks so I'll have a lot of the season left.
"I'd rather take my time now than rush it and have problems for the rest of my career."