The submarine was launched Thursday in a ceremony held in St. Petersburg, Xinhua reported.
A navy official said that the new diesel-electric submarine Rostov-na-Donu, along with other vessels in the ongoing Project 636 series, represented modernisation of existing Russian submarine technology.
"The outside remains the same, but inside is completely different: a new torpedo defence system, new acoustic technology and new radio-electric equipment," the official said.
Rostov-na-Donu will join its Project 636 sub Novorossiysk for Black Sea duties which will include working together with surface forces and anti-submarine aircraft.
As well as covering the Black Sea, the new sub is also set to assist Russian naval activities in the neighbouring Mediterranean Sea.
Over the next few years, a total of six diesel-electric submarines would join the Black Sea Fleet under Project 636.
The vessels are designed to combine a high level of stealth with the ability to detect and attack enemy craft from a long range.
Project 636 is part of a broader development strategy for Russia's Black Sea Fleet.
Russian Defence Minister Sergey Shoigu promised an investment of more than 86 billion rubles (about $2. 55 billion) in the Black Sea Fleet by the year 2020.