Paul Leser was born on February 23, 1899 in Frankfurt am Main, Germany, the youngest of Wilhelm and Helene (Rikoff) Leser's three children. He attended schools in Frankfurt and was graduated from the Goethe Gymnasium in 1917 with his Abitur. That year, Leser was inducted into the German Army and served in World War I; he later became ill and recuperated in the Army Hospital. During his hospitalization, he began taking classes at the University of Bonn. In 1919, he became a member of the Nerother-Bund, a part of the German youth movement which was founded by the brothers Karl and Robert Oelbermann. Also in that year, he returned to the University of Bonn to study under his mentor Fritz Graebner, one of the principal exponents of the cultural-historical approach to ethnology. He graduated from the University of Bonn with his Ph.D. in 1925.

Leser held positions at the Frankfurter Bund für Volksbildung and at the Ethnological Museum in Frankfurt before becoming a Privatdozent for Ethnology at the Darmstadt Institute of Technology. During this time period he became involved in the case against Dr. Julius Lips of the Raustenstrauch-Joest Museum, who was accused by Leser and others of plagiarizing from the works of Graebner, Schmidt, and Koppers. The case dragged on until 1933, when many of the participants were removed from their positions by the Nazis. Though the case took up much of his time in the early 1930's, his main interest was his own work on the history of the plow. In 1931, his most renowned work Entstehunq und Verbreitung des Pfluges was published (it was eventually reprinted in Denmark in 1971).

In 1936, because of the increasingly hostile political climate in Germany, Leser was forced to immigrate to Sweden. He took a position as translator for Folk-Liv in Stockholm. In 1941, he immigrated to the United States. Leser served in the United States Army in North Africa, Sicily, and Italy from 1942-1945. After the war, and a brief stint as a civilian employee at the U.S. War Department, Leser returned to the world of academia. Beginning in 1947, he held positions as Professor of Anthropology at Olivet College in Michigan, Black Mountain College in North Carolina, and The Hartford Seminary Foundation in Connecticut. In 1967, he retired from his teaching position at the Hartford Seminary and became an Emeritus member of the faculty. At the time of his death in December of 1984, Leser was a Research Professor of Anthropology at the University of Hartford. Leser died in Hartford at the age of 85 and was buried in the family plot in a cemetery in Frankfurt am Main.