Otto II, Count of Rietberg (died 18 July 1389) was the ruling Count of Rietberg from 1365 until his death.
He was the son of Conrad III and his wife Ermeswint of Reifferscheidt.
He died on 18 July 1389 and was buried in the Marienfeld Abbey.
Around 1370, Otto II married Adelaide, the daughter of Otto of Lippe from the neighboring County of Lippe.
This article about a member of the German nobility is a stub.