Meanwhile 290,000 children were living in homes where money was tight, down 5000 (1 per cent) from the previous year.
Children's Commissioner Judge Andrew Becroft said the figures were positive, but progress made under the previous government needed to be sustained.
"We have seen a small drop in the number of children living in households on low incomes, or lacking the items they need for everyday living," he said.
"But there are still 290,000 children in households on low incomes and up to 135,000 children lacking basic items."
Becroft said it was encouraging to see the measures the new Labour-led government had put in place as part of its first 100 days work programme.
Prime Minister Jacinda Ardern had pledged throughout her election campaign to end child poverty and created a role of minister for child poverty reduction, which she took, once in government.
Despite the progress made this year, and promises of continued support for children and families in need, Becroft urged politicians and those working in the sector not to get complacent.
"We can see for the first time some real progress towards wiping out child poverty, but it will take many small steps to get there.
"It is essential we keep up this momentum. One small step will not be enough. We need to see changes like these every year to see a substantial long-term decrease in poverty, and ensure these gains are not cancelled out by increases in the cost of living."
Ardern welcomed the improved numbers but said thousands of children were going without and she was prepared to be held to account for improving their lot.
"The Families Package and my Child Poverty Reduction Bill will have a significant impact on families who are struggling to pay for the basics for their children and will ensure the public can track our progress," she said.
"Details of the package will be announced next week. It's targeted at those who need support the most, and will be much more effective at lifting children out of poverty than the Opposition's plan.
"My Poverty Reduction Bill is an opportunity to reach a long-term commitment to tackle child poverty and I'm keen to work with the Opposition to make that commitment durable."
National's spokesperson for children Paula Bennett said it was "great news" that 50,000 children were no longer in poverty.
"It further consolidates our track record as a party that shows it cares. It mainly goes back to the benefit changes and increases we made in 2015 - those are genuinely making a difference for families."
National's 2011 welfare reforms, which moved many people off the benefit, had also contributed to the improved numbers as many more parents were now in work, Bennett said.
Bennett said National would need to see the details before signing up to Labour's Child Poverty Reduction Bill.
"If she really wanted cross-party support she will have other parties involved in designing it. We're really keen to look at it on its merits.
"It's got to have a means to identify the children, a way to measure the success of whatever the intervention is."
The Child Poverty Monitor report, funded by the J R McKenzie Trust, an organisation with over 75 years of involvement in important social issues, was in its fifth year.
Trust executive director Robyn Scott said the report helped track the country's progress towards helping get its youngest citizens out of poverty.
It is a joint project by the Children's Commissioner, J R McKenzie Trust and Otago University NZ Child and Youth Epidemiology Service (NZCYES) that tracks progress through a number of measures, including material hardship and family income.
Scott said it was important for New Zealanders to realise all could play a part in helping alleviate child poverty.
"The Government initiatives are very welcome, but we mustn't lose sight of the fact that everyone can play a part in improving children's lives.
"Community groups, businesses, schools and individuals can also help by providing the range of opportunities and experiences all children need."
Epidemiology Service director Dr Mavis Duncanson said all children deserved to get what they needed to be physically and mentally well.
"A warm dry home, a sustaining meal with vegetables and protein regularly, clothes and shoes that fit properly, a place to study quietly, and the use of a computer and internet at home.
"Children in households with the lowest material living standards are much more likely to lack these basic needs as well as miss out on the experiences and life chances that we would want for all children."
REPORT FINDINGS
• 12 per cent of children are living in material hardship. That means 135,000 New Zealand children are in households without seven or more items, from a total list of 17, which are considered necessary for their well-being. This is down from 14 per cent or 155,000 in 2016.
• 6 per cent (or 70,000) of New Zealand children are experiencing even worse material hardship in households missing out on 9 or more items from the list of 17. This is down from 8 per cent, or 85,000, last year.
• 27 per cent of children are in low income homes. That means 290,000 New Zealand children are in homes where money is tight and are considered to be in income poverty. This is down from 28 per cent or 295,000 in 2016.
• More than 7 per cent of children are in severe poverty. That means 80,000 New Zealand children are experiencing material hardship and living in a low income household. This is down from 8 per cent or 90,000.
Child poverty has been reasonably stable for a number of years, but it is significantly worse than in the 1980s. In 1982, the percentage of children in families experiencing income poverty was 14 per cent, compared to 27 per cent now.
An earlier version of this article stated that 50,000 children had been helped out of poverty. However, this figure did not take into account the fact children were represented across several measures. Therefore, the more accurate statement is 10,000 children were helped out of severe poverty, while material hardship for 20,000 has been reduced.
