The parents spent two hours playing slot machines and drinking at the casino bar on the morning of February 26 while their five children, aged between 11 months and nine years, were left in a van in the casino carpark.
According to the police summary, the woman took "one minute" to check on the children after an hour before returning to the slot machines.
The children were found after a couple heard "hysterical crying" from the van and called police.
Judge Grant Fraser said police opposed the application for a discharge without conviction, and the five children had been exposed to danger.
"You behaved in a manner where there was a complete lack of judgment on your part," Judge Fraser told the woman.
"In effect, you left the children for a period of two hours unattended, although I accept that after one hour you did go back to check on them."
But he said the woman had voluntarily booked herself into an institution to undergo counselling.
Her children were put into Child Youth and Family care, but they have since been returned to her.
He also took on board submissions made by the woman's lawyer, Richard Slade, who said his client hoped to one day become a social worker.
Judge Fraser said the woman's partner did not meet the test to be discharged without conviction because he had other criminal convictions.
He convicted the man, and ordered him to pay $132 court costs.
"A conscious decision was made by you to gamble while the children were in the vehicle and they were left in a particularly careless and dangerous situation," he said.
University of Auckland law professor Warren Brookbanks said the couple should consider themselves lucky the charge was laid under the Summary Offences Act, rather than the Crimes Act which carries a harsher penalty.
"Had the children suffered injury, or death at the very worse case scenario, they would have been liable under the Crimes Act for a new offence which has been enacted recently, of failing to protect a child, and the penalty, I think, is in excess of two years' [prison] maximum penalty."
Being discharged without conviction was the lowest penalty the mother could have got, "so they should consider themselves very lucky that the police didn't lay more serious charges".
Department of Internal Affairs figures show the number of cases of children being left unattended at SkyCity has almost tripled in two years. There were 54 incidents of children being left unattended last year, up from 46 in 2010 and 19 the year before.
