Lev Platonovich Karsavin, a renowned Russian religious philosopher, cultural historian, and medievalist, was born on December 1, 1882, in St. Petersburg. He was the son of ballet actor of the Mariinsky Theatre Platon Konstantinovich Karsavin and Anna Iosifovna Khomyakova, whose father was a cousin of the famous Slavophile A. S. Khomyakov. Lev was the brother of ballerina Tamara Karsavina.

Karsavin studied under I. M. Grevs and graduated from the historical and philological faculty of St. Petersburg University in 1906. From 1909, he taught at the Historical and Philological Institute, becoming a professor in 1912 and an inspector in 1914. He also worked at the Higher Women's (Bestuzhev) Courses and was a privat-docent, later becoming a professor at St. Petersburg University.

In August 1922, Karsavin was arrested and sentenced to exile abroad without the right to return. He was released shortly before the exile and in November 1922 was sent from Soviet Russia on the 'philosophical steamer' along with a group of forty-five figures from science and culture.

At the end of 1927, Karsavin received an invitation to take the chair of universal history at the University of Lithuania in Kaunas, which later became Vytautas Magnus University. From 1928, he lived in Kaunas and taught universal history in Lithuanian. After Lithuania joined the USSR, Karsavin remained in the country and became a professor at Vilnius University after the humanities faculty was transferred there in 1940. From 1941, he also taught at the Art Institute and worked for some time at the Art Museum.

In 1944, Karsavin was removed from teaching at Vilnius University and dismissed from the museum. In 1949, he was dismissed from the Art Institute, arrested, and accused of participating in the anti-Soviet Eurasian movement and preparing to overthrow the Soviet government. In March 1950, he was sentenced to ten years in a corrective labor camp. Lev Karsavin died of tuberculosis in a special camp for the disabled in the village of Abezy, Komi ASSR, in July 1952.