The boy was struck with enough force that it left marks that were noticed at his school, which wanted him examined to ensure he had not suffered any long-term injuries.
He suffered bruising and redness to his skin and had to receive medical attention.
Judge Fitzgerald said the assault was "inappropriate force used for discipline''.
"In a sense, he was reliant on you to respond to the situation which led to the assault appropriately. The fact that you didn't is, in a sense, a breach of trust, which I need to consider.''
The man had applied to be discharged without conviction on the grounds that a criminal record would interfere with his numerous speaking responsibilities, and his position within charity and community organisations.
Another consequence could be the embarrassment of having to declare the conviction at customs, which could mean being refused entry into some countries.
He had entered a guilty plea at the earliest possible opportunity, accepted responsibly for his actions and voluntarily undergone an anger management course.
The court was told that he was much loved by his family, including his son who was protective of his father because of the consequences the assault had already had.
The police did not oppose the discharge without conviction application.
However, Judge Fitzgerald decided it was necessary to convict the man, given New Zealand's ongoing problem with child abuse.
Significant mitigating features - including the man's contributions to his community, and his otherwise clean record - meant further punishment was not necessary.
Legal experts have criticised the decision to grant the man name suppression.
Suppression was reportedly granted because of his standing in sporting circles and in the community, as well as to protect the identity of the complainant.
The Criminal Procedure Bill, which was passed in October, makes it clear that "wealth, reputation or public awareness'' should not be factors in gaining name suppression.
It allowed for a strong presumption of open justice, Auckland University Faculty of Law associate professor Scott Optican told the Herald in November.
"In terms of the current law this is one of the reasons the Criminal Procedure Bill was passed because name suppression is so open ended and often goes out without any explanation or rationale from the judges at all. It doesn't mean it's not justified in some cases ... but the current provision that allows it is very broad-based,'' he said.
"Perhaps the victim, who is a child, would be identified. That would be the only exception I'm willing to give if it compromises, identifies, embarrasses the child ... sportsmen should not get name suppression because they're sportsmen ... if a child is involved and could be identified then I could maybe see what the district court is doing.''
