Three men found guilty of war crimes during the 1991-2002 civil war.
The three men were leaders of the Armed Forces Revolutionary Council (AFRC), a junta that overthrew an elected government in 1997 and was removed from power by a Nigerian-led peacekeeping force the following year.
The ruling marks the first time an international court has issued a conviction on the conscription of child soldiers, who in Sierra Leone were often drugged and forced into battle.
Announcing the unanimous verdict of the three judges, Sebutinde said none of the defendants had expressed genuine remorse.
Corinne Dufka, a senior researcher for Human Rights Watch, said: “The AFRC committed unspeakable horrors against civilians throughout the towns and villages of Sierra Leone.
“Today, the victims of these crimes have seen justice served; tomorrow, future perpetrators have been put on notice that wars have rules, and they must be respected.”
The special tribunal was set up following the end of the diamond-rich country’s 10-year conflict in 2002 to prosecute war crimes.
About half a million people died during the fighting, victims of systematic mutilation in which rebels raped, pillaged and cut off the limbs of thousands of civilians.
Some critics say the special court is working too slowly.