Miller was a nobleman of German descent. He graduated from the Nicholas Cavalry School (1886) and Nicholas General Staff Academy (1892). In 1898–1907, he was a military attaché in Belgium, the Netherlands, and Italy. Since 1910, he was the Chief of the Nicholas Cavalry School. Since October 1912, he was Chief-of-Staff of the Moscow Military District. A participant of World War I, Lieutenant General (1915). Since the end of 1916, he commanded the 26th Army Corps.

In April 1917, he was beaten and arrested by soldiers of the corps, whom he had ordered to take off the red bows, and was sent under escort to Petrograd. After an investigation that did not find any evidence of a crime, he was discharged to the reserve. Since August 1917, he was under the authority of the Chief of the General Staff, as a representative of the Stavka (Headquarters) of the Supreme Commander-in-Chief in the Italian headquarters.

After the October coup of 1917, he was engaged in the redeployment of personnel of Russian brigades in France and Macedonia to Russia to fight the Bolsheviks. In November 1918, he received an invitation from the Provisional Government of the Northern Region to take up the post of Governor-General.

On January 1, 1919, he arrived in Arkhangelsk, where he was appointed an administrator of the government responsible for foreign affairs, and on January 15 was promoted to Governor-General of the Northern Region. According to the decree of the Supreme Ruler of Russia Aleksander Kolchak dated June 10, 1919, the troops and the fleet of the Northern Region were united with the Siberian Armed Forces, and Miller was appointed Commander-in-Chief of all land and naval armed forces in the North of Russia (Northern Front) while retaining the post of Governor-General.

After the fall of the Northern Region in February 1920, he emigrated to Norway, then to France. Miller’s subsequent career included the following: Since May 1920, General Pyotr Wrangel’s Chief Plenipotentiary for military and naval affairs in Paris. Since 1930, Chairman of the Russian All-Military Union (ROVS), an organizer of ROVS’s terrorist activities in the territory of the USSR. In 1937, in Paris, he was kidnapped by agents of the People’s Commissariat of Internal Affairs (NKVD) and smuggled to Moscow, where he was sentenced to death by the Military Collegium of the Supreme Court of the USSR, and shot.