Zouma started against Watford despite intense backlash over his shocking video of himself abusing his pet cat.
The controversial decision to start the Frenchman was condemned by fans and critics when the team-sheet was announced before kick-off.
Moyes justified his selection by claiming Zouma is one of the 'better players' and says he's responsible for getting results.
However, the Scot naming Zouma doesn't sit well with O'Hara as he believes the West Ham gaffer should've punished the 27-year-old for his sickening actions.
"I’m ashamed of David Moyes," he told talkSPORT.
"And I love David Moyes, he’s a great manager and he never really gets anything wrong. I think he’s top drawer."
The former Tottenham star added: "But I think he’s got this one wrong with Kurt Zouma. He should’ve punished him, he shouldn’t have been playing and it’s absolutely unacceptable what they’ve done.
"What they’ve done is basically say to condone what he’s done because they played him.
"I know it’s a football situation, he needs to put the best team out, but this is more than football. It’s more than football.”
Moyes' selection of Zouma will continue to come under scrutiny ahead of his side's next Premier League match.
After moving above Manchester United to fourth place, the Hammers resume their league campaign at Leicester City.
Zouma has played 13 league games this season and could keep his place in the starting XI for Sunday's game.
Featured Image Credit: PA