Gryaznov (Russian: Грязнов, from грязь meaning mud) or Griaznov is a Russian masculine surname, its feminine counterpart is Gryaznova or Griaznova. Notable people with the surname include:
- Alla Gryaznova (born 1937), Russian economist
- George Gryaznov (1934–2011), Russian Orthodox archbishop
- Vadim Gryaznov (born 1986), Russian football player
- Vasiliy Griaznov (c. 1840–1909), Belarusian painter, art teacher and historian
- Vyacheslav Gryaznov (born 1982), Russian classical pianist, transcriber and composer