Mikhail was born in Saint Petersburg to the family of Intelligentsia. His grandfather, father and aunt were professional writers. His uncle Semyon Vengerov was a famous philologist and literary critic. His older brother Nicolas Slonimsky became a famous composer.
In January 1915 after graduating from his gymnasium Mikhail went as a volunteer to Russian Army to fight in World War I. He was awarded St. George medal was wounded returned to the front, wounded again and evacuated to the Petrograd (Saint Petersburg) hospital.
Since 1917 Mikhail published his works regularly (his first publication was in the magazine New Satiricon of 1914). He was one of the founders of the Serapion Brothers group. The group met at his apartment and according to some memorises, he was the inventor of the name.
Later Mikhail evolutioned to a typical Soviet writer and an administrator of the Union of Soviet Writers.
Mikhail's son, Sergei Slonimsky is a notable Russian composer