The move was the largest single release of child recruits since Myanmar's new reformist government and its "tatmadaw" army signed a June 2012 pact with the UN on the issue.
A total of 272 children and young people have been released over the past 18 months as the military has slowed -- but not yet completely halted -- its use of children.
The release was "an historic step towards ending the recruitment and use of children by the Myanmar Armed Forces," the United Nations said in a statement.
There are no verifiable figures on how many children are currently serving in Myanmar's huge military, which has faced a slew of accusations over rights abuses, including the forced recruitment of children and other civilians to work as porters or even human mine detectors.
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Ending rights violations is a key demand of the international community, which has embraced reforms in Myanmar since the end of outright junta rule in 2011.
Myanmar released 42 children in September 2012, 24 in February last year, 42 in July and a further 68 in August.
All of those freed were recruited as children, but some have since become adults.
The UN also voiced concern that seven armed ethnic rebel groups in the country continue to recruit children into their ranks and called for an end to the practice.
Myanmar has been gripped by a number of civil conflicts with ethnic minority groups seeking more autonomy since independence from British colonial rule in 1948.
The current government has reached tentative peace deals with most rebel groups, but a nationwide ceasefire has so far proved elusive.