The L-24 submarine with 57 submariners onboard disappeared off Bulgaria's Cape Shabla in December 1942 after it is was hit by an underwater Romanian mine.
The submarine was located by Bulgarian divers in 1991, but work to identify the vessel was only carried out on June 2 by a Russian-Bulgarian expedition. Russian divers identified the submarine on Friday after reading a mark on the bow.
The memorial to the 57 submariners was created on Sunday in both Russian and Bulgarian languages. The memorial message read: "We remember, are proud and mourn."
The deaths of the L-24 submarine crew were the biggest loss for the Soviet Fleet during World War II, known as the Great Patriotic War in Russia and other former Soviet states.
An expedition member Mikhail Zaimov said: "People should not be divided into Bulgarians and Russians. These people are heroes who lost their lives for the common future. The history is the one for all."