Pyotr Krasnov was born in St. Petersburg. He descended from a famous Don Cossack family. Krasnov graduated from the First Military Pavlovsk School (1888), served in the Life-Guard Ataman Regiment. In 1901, he was sent to the Far East to study the countries of the region. He was a war correspondent during the Yihetuan (Boxing) Uprising in China and the Russo-Japanese War. In 1909, he graduated from the Officer Cavalry School. A participant of World War I, Major General (1914). July 1915, Chief of the 2nd Combined Cossack Division.

In August 1917, while Lavr Kornilov was delivering his speech, he was appointed Commander of the 3rd Cavalry Corps. However, by the time he took office, the offensive had failed. He was briefly arrested over supporting Kornilov and soon acquitted.

After the October coup of 1917, by order of Aleksander Kerensky, he sent part of the units of his Corps to Petrograd, that seized Gatchina and Tsarskoe Selo. As no reinforcement was sent to support him, Krasnov surrendered to the Bolsheviks. He was released after a few days.

He left for the Don area, where in May 1918 he was elected Ataman [commander] of the Great Don Host. With the support of German troops, he established the Don Army. By mid-August, these forces had overthrown the Soviet power in most of the territory of Don Host Oblast [province]. By the decision of the Great Host Circle [assembly], he was promoted to General-of-the-Cavalry (1918).

Krasnov advocated the concept of the establishment of an independent Cossack state on the Don. In January 1919, after losing the support of Germany and being defeated at Tsaritsyn, he agreed to join the Volunteer Army and establish Armed Forces of the South of Russia (AFSR) under the command of Anton Denikin, who relied on the Entente. In February 1919, Krasnov resigned and left for Germany as a result of his differences with the command of the AFSR. In September 1919, he presented himself to the service of Commander of the Northwestern Army, General Nikolay Yudenich. After the defeat of the Army, Krasnov negotiated with the Estonian authorities on the evacuation of military personnel.

Since 1920, he was in exile, lived in Germany and France. Krasnov was engaged in literary activities, collaborated with the Russian All-Military Union, and was involved with various monarchist organizations. During World War II, he collaborated with the Nazis, in 1943 he took command of the Main Directorate of Cossack Troops in Germany. In 1945, he surrendered to British troops and was handed over to the Soviet military administration. He was sentenced to death by the Military College of the Supreme Court of the USSR and hanged.