Justice Jon Kamanda was elected to a one-year term as presiding judge of the appeals chamber, a post that automatically makes him the tribunal's president as well, the United Nations said in a news release.
The war crimes tribunal, backed by the United Nations, was established to address the worst acts committed during the long, brutal civil war in the African nation.
Justice Emmanuel Ayoola of Nigeria was elected as vice president.
Kamanda, who succeeds Renate Winter of Austria, worked as a barrister, prosecutor and judge during the past 34 years, the United Nations said. He has also served as a government minister in Sierra Leone.