After graduating from high school, Ozerov enrolled for the Lunacharsky State Institute of Theatre Arts in September 1939. A month later, he was drafted into the Red Army, where he was trained as a signaler. When Germany invaded the Soviet Union, he held the rank of a Second Lieutenant. Ozerov participated in the Battle of Moscow and in the campaigns for Ukraine and Poland. In 1944, he underwent a staff officers' course in the Frunze Academy. While stationed in the 3rd Belorussian Front, he took part in the Battle of Königsberg as a forward observation officer. In a 2001 interview, he told that the battle had a profound effect on him and he swore that if he will remain alive, he would "tell the story of the great army that fought in the war." After the German surrender in May, Ozerov served in the occupied city until his discharge in October 1945, with the rank of a Major. During the war, Ozerov married a nurse, Raisa Sukhomlina, with whom he had a son, Vladimir. The two later divorced.