"The Brussels appeals court finds in favour of the appeal of the Belgian state "against a lower court's decision handed down on December 26, it said in a statement, confirming that "the Belgian state is no longer obliged to undertake any act of repatriation."
Another court had previously rejected a demand lodged by two women, each mother to three of the children, for their home government to intervene.
But the Flemish-speaking Court of First Instance in Brussels overturned that with its December ruling, ordering Belgium to take "all necessary and possible measures" to bring the children home from the Al-Hol refugee camp, overseen by Kurdish forces, near the Iraqi border.
Human rights campaigners welcomed that ruling.
The children, all aged six or under, are the offspring of alleged jihadist fighters. Human rights groups fear as many as 160 Belgian minors are trapped in the Syrian conflict zone.
The December ruling gave the Belgian state 40 days to comply or face fines of 5,000 euros (almost $5,700) per child per day.
As a proportion of its population, Belgium has been one of the main suppliers of Europeans travelling to fight for Islamist extremist groups in Syria and Iraq.
In all, more than 400 adults are thought to have left to join groups such as Islamic State or Al-Qaeda since 2013.
Belgium has been hit by several attacks claimed by IS, notably the Brussels attack in March 22, 2016 which killed 32 people.
The Belgian government has said it is willing to "facilitate the return of children (of jihadists) under the age of ten whose descent from a Belgian parent is proven. But for the remainder it is on a case-by-case basis."
European governments fear returning extremists will bring violence home, but the presence of non-combattant family members has complicated security policy choices.
