Sander was born in Herdorf, near Cologne, Germany, the son of a mining carpenter. The young Sander began an apprenticeship as a miner in 1889. He received a 13 x 18 cm camera from an uncle in 1892, built a darkroom, and began to photograph in his spare time. After military service, he toured Germany as a commercial photographer specializing in architectural and industrial photos. In 1901 he was employed by the Photographic Studio Graf in Linz, Austria. He and a partner bought this concern the following year and renamed it Studio Sander and Stuckenberg. Two years later he bought out his partner and started the August Sander Studio for Pictorial Arts of Photography and Painting.
Sander was awarded a gold medal and Cross of Honor at the Paris Exposition of 1904, the first of hundreds of such awards he would receive in his career. He began at this time to experiment with color photography and his work in this field was soon acquired by the Leipzig Museum. In 1906 Sander's first one-man exhibition, of 100 prints, was held at the Landhaus Pavilon in Linz.
After selling his studio in Linz, Sander moved his family to Trier and then to Lindenthall, a suburb of Cologne. While photographing peasants in nearby Westerwald, Sander originated his life-project, "People in the Twentieth Century." His intention was to document the entire German people. While pursuing this work, he continued to photograph industrial and architectural subjects to make his living.
Sander served in the German Army during World War I but continued to photograph. He began teaching apprentices and other students in 1919.
In 1927 Sander travelled to Sardinia to photograph the people and landscapes. This was his only trip outside Germany.
Late that year he showed 60 photographs from the "People in the Twentieth Century" series in the Cologne Kunstverein exhibition. This show led to an agreement with the publisher Kurt Wolff to issue books covering the entire project. The first of these volumes, Face of Our Time, appeared in 1929 with an introduction by Alfred Doblin.
Sander delivered a series of highly popular radio lectures on "The Nature and Development of Photography" in 1931. The rise of Hitler began to affect his work about this time.
His son Erich joined the Socialist Worker's Party and anti-Nazi movement in 1933; he was jailed for treason in 1934 and died in prison 10 years later. At the same time (1933-1934) five books of Sander's "German Land, German People" series were published. They met with immediate disapproval by the Nazi authorities and he was forced to cease work on "Man in the Twentieth Century." His Face of Our Time was seized, the plates destroyed, and negatives confiscated by the Ministry of Culture.
Sander began a series of Rhineland landscapes and nature studies in 1935 on which he worked for the rest of his life. During World War II he made prints of pre-war photographs for families of men who had died or were missing in action. He began some work on "Man in the Twentieth Century" once more. His studio was destroyed by bombing, but thousands of negatives were salvaged. Tragically, the same negatives were destroyed by looters in 1946. Despite these setbacks, Sander continued to work on a variety of special projects and books.
In 1951 Sander's work was mounted at the first exhibition at Photokina. His documentation of pre-war Cologne was bought by the city the same year. A number of his photographs were selected by Edward Steichen in 1952 for inclusion in the Family of Man show of 1955.
Sander was named an honorary member of the German Photographic Society in 1958 and was given a one-man show by that body the following year. He received the Order of Merit of the Federal Republic of Germany in 1960. Sander suffered a stroke in late 1963 and died in Cologne some months later.