Russia–South Korea relations or Russian–South Korean relations are the bilateral foreign relations between Russia and South Korea. Modern relations between the two countries began on September 30, 1990. Due to the 2022 Russian invasion of Ukraine, relations became very tense after South Korea imposed sanctions against Russia. Russia placed South Korea on a list of "unfriendly countries", along with Taiwan, Japan, Singapore, the United States, European Union members, NATO members, Canada, Australia, New Zealand, Norway, Switzerland, Micronesia and Ukraine.

Koryo-saram or Koryoin are ethnic Koreans in the post-Soviet states who descend from Koreans who were living in the Russian Far East.