45% of the complaints received were about education, with the Ombudsman calling for more Government oversight in the sector
The Ombudsman for Children's Office (OCO) dealt with 1,639 complaints made by, or on behalf of, children in 2015.
The Ombudsman has published the office's annual report today.
The complaints figure marks an 8% increase in the number of complaints received compared to 2014. It is also the highest number of complaints since the OCO came into operation in 2004.
The office also says it had "successful interaction" with 850 children and young people last year.
Ombudsman Dr Niall Muldoon said: "The range of issues dealt with by the OCO emphasises that children’s lives cannot be compartmentalised, that problems can be complicated and that cooperation between all departments is vital to solve problems."
He highlighted that the largest number of complaints - 45% of the total - were received about education. 25% related to 'family support, care and protection', while the health sector made up 14% of complains.
On the subject of education, Dr Muldoon observed: “It is my view that the autonomy afforded to Irish schools means that the Government has not been able to exercise the necessary responsibility and oversight.
"It is time to recalibrate the balance between the autonomy of schools and the oversight by Government to advance and protect children’s rights within the education system," he added.
He also pointed out that children's rights in Ireland is an "unfinished project" and his team will continue to work towards "an Ireland where all children and young people are actively heard and respected".
The first Ombudsman for Children was appointed in December 2003, and the office aims to "promote the rights and welfare of children under the age of 18 living in Ireland".