The measure now heads to Belgium's House of Representatives where it's expected to pass.
The country already allows euthanasia for adults, but the new bill removes all age limits.
It's a decision many say a child is not equipped to make.
"The answer is caring. The answer is not killing," Carine Boucher, with the Center for Bio-ethics in Brussels, said.
"The child does have the maturity to get married or to buy alcohol or to buy cigarettes if he is 14. Now we are saying that because he is suffering he might have the possibility to ask for euthanasia," Boucher added.
The children would need parental consent and have to submit a written request to die.
Critics say Belgium's current euthanasia law has been abused. Some adults have been killed even though they were only depressed.