Up to a third of Kiwi parents say they smack their children as a form of discipline, and one in 10 parents admit they smack their children regularly.
The startling admissions have been revealed in the Growing up in New Zealand study.
Children's Commissioner Judge Andrew Becroft said he was not "particularly surprised" with the statistics, but he was "slightly disappointed".
"This is part of a social change, we're evolving in New Zealand and I look forward to the day that children aren't spanked," he told TVNZ 1's Breakfast.
He said it was not a sign the law had failed.
"I think there's been something of a sea-change."
Judge Becroft likened it to the perception of corporal punishment in schools currently, as opposed to the view of it before it was abolished.
"I'm quite confident as part of the social change, the evolution in societal attitudes that we're undergoing."
"We're changing, we're reducing smacking, we all know there are better ways to discipline kids."
"There's no debate that kids need boundaries, no debate that we need to set standards, but there are much more creative, effective and productive ways, than smacking."