Arne Kildal was born in Kristiania, the son of politician Birger Kildal. He finished his secondary education in 1903, and took the cand.philol. degree before traveling to the United States to train as a librarian. He graduated with a Bachelor of Library Science from the State University of New York in 1907 and worked in the country for three years, including at the Library of Congress.

In 1910 he returned to Norway to become chief librarian at Bergen Public Library. From 1920 to 1925 he served as the Norwegian press attaché in Washington, D.C. In 1925, he took over as secretary general of Nordmanns-Forbundet, a cultural association for Norwegian-Americans, and served from 1925 to 1955, only interrupted by World War II from 1941 to 1945. He was also employed by the Norwegian Ministry of Church and Education from 1937 to 1949. In 1949 he was appointed as the first director of the Norwegian Directorate of Public Libraries, serving until 1956. Kildal chaired the Norwegian Library Association from 1913 to 1916 and 1929 to 1933, and the Statens folkeopplysningsråd from 1933 to 1950.

Kildal was decorated with the Order of the Dannebrog and the Order of St. Olav.