Leonid Buber was born in 1916 in Nikolaev, Ukraine. After completing his apprenticeship at an industrial school, he worked as a lathe operator in a shipyard. He joined the Red Army in 1935 and after graduation from infantry school became a staff officer. In 1939 Leonid Buber took part in the annexation by the Soviet Union (following the Molotov-Ribbentrop Pact) of Western Ukraine and in 1940 of Northern Bukovina. He also fought on the Finnish front during the Winter War between the Soviet Union and Finland (November 1939-March 1940). In April 1940 Major Buber was awarded the medal of Hero of the Soviet Union for valor demonstrated during the fighting at the Mannerheim Line.
After the outbreak of war on June 22, 1941, Leonid Buber participated in the formation of the 16th Infantry Lithuanian Division and, from 1942, served as assistant commander of the Division's 167th Regiment. In early July 1943, during the battle of Kursk (July-August 1943), the Germans attacked Buber's regiment with tanks and infantry supported by aircraft near the Kursk salient. His men destroyed 13 out of the 20 tanks, but when the German infantry recovered, it launched an attack intended to cut the Soviet defense line in two. Leonid Buber led his men into battle three times. Although he was severely wounded (he was later evacuated to the Moscow hospital), he did not leave the battle field. Buber's men were reinforced by troops under the command of the Jewish officer Vulf Vilenskii and after three days of fighting the Germans failed to break through the Russian defenses. This successful battle enabled Red Army troops to liberate the nearby city of Orel shortly afterwards. On July 6, 1943 Leonid Buber was decorated with the Order of the Red Star for his role in the battle. Apparently during this period of time also, he was awarded the Order of Lenin.
In the speech he delivered at the 3rd Anti-Fascist Meeting of Jewish representatives, held in Moscow on April 3, 1944, Buber stressed the leading role of many Jewish soldiers and officers, men and women, in different forces of the Red Army and emphasized that one of their motives in fighting the Nazis was to take revenge for their murder of Jews:
“… Comrades, our love for our motherland and our hate for the [German] executioners of our [Jewish] people, … these sacred feelings lend us wings in battle, inspire us to heroic deeds… to fight and to win every battle. Victory is near. We will soon be at the threshold of the enemy's home. … then we will settle accounts completely for Babi Yar in Kiev, for the thousands of anti-tank trenches in other towns where the bodies of innocent civilians [i.e. Jews] brutally murdered by the Germans lie. We shall take revenge on them for everything!”
From 1945 until 1948 Leonid Buber was a member of the Jewish Anti-Fascist Committee (JAC). In the wake of Stalin's post-war antisemitic repressions, and the dismantling of the Jewish Anti-Fascist Committee in 1948, with the arrests of prominent JAC members in 1949 culminating in their death on 12 August 1952, Leonid Buber moved with his family to Soviet Central Asia. In 1957, upon returning to Moscow, at his request he was discharged from the army with the rank of colonel and subsequently was given responsibility for military preparations at a Moscow high school.
Leonid Buber died in 2005 in Moscow. In July 2011, during a public ceremony held at the Ammunition Hill (Givat hatahmoshet) Museum and National Memorial Complex in Jerusalem a memorial plaque was dedicated to Leonid Buber.