It's 2019 annual report has been published today, and shows almost half of the 1,503 complaints were education related.
One fifth of the issues raised were linked to family support, care and protection with just 14 per cent of the total associated with health.
In 2019, 5 per cent of complaints made to the ombudsman related to housing, marking no change from 2018 figures.
However, Ombudsman Dr. Niall Muldoon says the homeless crisis and the pandemic are having an impact on children's mental health.
"Children and young people are feeling very stigmatised and stressed by living in homeless situations. They talk about having to hide it and keep it a secret.
"There's also the increase in poverty and limiting of financial resources available to a lot of families in the future.
“The Office remains concerned about the slow pace of change to improve law, policy and provision in the area of children and young people’s mental health.
“From my perspective as Ombudsman for Children, key issues for children and their rights that I want to see Government and the State pursue during 2020 include making tangible progress on putting in place a mental health system for children that is fit for purpose and upholds children’s right to the highest attainable standard of mental health.
"I would also like to see the homelessness crisis addressed as a matter of urgency, ensuring that meaningful steps are taken on the issue of enumerating the right to housing in our Constitution. New political commitments to address and indeed end Direct Provision are welcomed and I hope that these will be honoured in the quickest possible timeframe,” added Dr Muldoon.