All 13 proposed amendments seeking changes in the bill were defeated.
Daniel Bacquelaine, a physician and leader of the centrist Reform Movement, said it is wrong to think life and death questions should be reserved for adults. He stressed that the law imposed no obligations, and that no child, family or doctor would be forced to apply it.
The law will go into effect when signed by King Philippe. The Belgian monarch is not expected to oppose the measure, said Jean-Jacques De Gucht, a co-sponsor.
Belgium's euthanasia law, passed in 2002, previously applied only to legal adults. The neighboring Netherlands allows euthanasia for children as young as 12, providing their families agree.