Hegemann was the son of Ottmar Hegemann (1839-1900), a mirror and picture frame manufacturer in Mannheim, and Elise Caroline Friedrich Vorster (1846-1911). He attended boarding school first in Büdingen (1895-96), and later at Gymnasium Schloss Plön, from which he graduated in 1901. He began college studies in Berlin, studied art history and economics in Paris and economics at the University of Pennsylvania and in Strasbourg, completing his doctorate in Munich in 1908. Returning to the US, he visited Philadelphia and New York and worked for the "Boston 1915" Exposition, held in Boston in 1909.
Back in Berlin, the following year he was made general secretary of the first international city planning exhibition to be held in Berlin, in 1910. The exhibition aroused great interest and was reprised in refocused form in Düsseldorf; Hegemann wrote an article about it for a general audience and a two-volume official book.
In 1913 he was invited by the People's Institute in New York to give lectures on city planning in over 20 American cities. Again traveling widely, after publishing an extensive report on the Californian cities of Oakland and Berkeley, in early 1914 Hegemann embarked by ship on a return voyage to Germany via the Pacific, in order to visit the Far East. In July, 1914, he boarded a German flagged ship in Australia for the final leg of the journey home. Off the coast of Africa that August, World War I broke out and Hegemann's German ship dodged English warships for several weeks before being sequestered off the coast of Mozambique and refused permission to depart. In April, 1915, Hegemann stowed-away on a Norwegian vessel to finally leave the area, and made his way back to the United States for the duration of the war. In 1915 he worked as a city planning consultant. In 1916 he established a firm specializing in suburban planning based in Milwaukee, Wisconsin, with landscape architect Elbert Peets as his partner. In 1918, visiting a friend at the University of Michigan, Hegemann met his future wife, Ida Belle Guthe. In 1922 Hegemann and Peets together published a "thesaurus" of civic art for architects, commenting on about 1200 examples of the discipline, The American Vitruvius.
Returning to Europe with his new bride in 1921, in 1922 Hegemann built a home in Nikolassee, outside of Berlin. During this time he became editor of Wasmuths Monatshefte für Baukunst, which became known for its international coverage of architecture and Hegemann's incisive critiques. He wrote debunking biographies of German heroes and, in 1930, the work for which he is best remembered, Das steinerne Berlin: Geschichte der grössten Mietkasernenstadt der Welt (Stony Berlin: History of the Largest Tenement City in the World), which combines historical and architectural criticism. In the introduction he wrote, "It is a German illusion to believe in the possibility of creating an intellectual capital as long as the so-called educated people are almost proud of their inadequate understanding of urban planning." He also wrote political articles and warned against the Nazis, culminating in the book Entlarvte Geschichte (History Unmasked – 1933). He fled Germany in February, 1933, upon publication of the latter book (dedicated sarcastically to Adolph Hitler). In May, 1933, Hegemann was denounced by the Nazi's as an "Historical Forger," and his books were burned in the Nazi book burnings.
After several months in Switzerland and France, Hegemann was invited by Alvin Johnson to teach urban planning at the New School for Social Research in New York beginning in November 1933. That October Hegemann left Europe for the United States with his family. Hegemann was one of many intellectuals essentially exiled by Nazi Germany in the 1930s. He was quoted upon arriving in New York City on November 4, 1933, as giving Hitler two more years of power in Germany. He did not think the German people would permit Hitler to remain in power for longer than that. Hegemann began lecturing at the New School and organizing assistance for intellectuals and scholars detained by the Nazis in Germany. In 1935 he was also retained as a lecturer at the Architecture School at Columbia University. Also in 1935 the Nazis seized Hegemann's house in Nikolassee. In early 1936 he became ill, first diagnosed with Sciatica, and then hospitalized with apparent pneumonia; While bed-ridden in New York City he worked on his last book, the 3-volume City Planning, Housing, intended to supplement and update The American Vitruvius, eventually completed by 2 co-editors, the last volume appearing in 1938. Hegemann died on April 12, 1936, at age 55 in New York. The treating doctor opined that the cause of death was Tuberculosis Meningitis. Hegemann's repeated travel between Europe and the United States, along with his strong education and broad interests, made him an intermediary between architects and city planners on both sides of the Atlantic: in particular in The American Vitruvius he refers extensively to European design, taking many examples from his book on the Berlin 1910 exhibition, while in Amerikanische Architektur und Stadtbaukunst he informs German architects of American solutions. However, his emphasis on urban planning rather than purely formal considerations and possibly his having not been present during the development of the Modern Movement in architecture in Europe put him at odds with modernists. For example, in 1929 he was forced to retract an accusation that Martin Wagner's primary activity as chief of city planning for Berlin was funnelling architectural commissions to extremist friends, and he labeled Le Corbusier's Ville Contemporaine project for transforming Paris "only vieux jeu" (old hat) and sarcastically predicted that it was likely to be realized,
[not] because [the skyscrapers] are desirable, healthy, beautiful, and reasonable from the perspective of urban planning but because they are theatrical, romantic, unreasonable, and generally harmful, and because it is part of the money-making activities of a metropolis, in what is literally the world's most international city, Paris, to serve the need for sensation and the vices of native and imported fools.
- Der Städtebau nach den Ergebnissen der Allgemeinen Städtebau-Ausstellung in Berlin, nebst einem anhang: Die Internationale Städtebau-Ausstellung in Düsseldorf; 600 wiedergaben des Bilder- und Planmaterials der beiden Ausstellungen, mit Förderung durch die königlichen preussischen Ministerien des Inneren, des Handels und der öffentlichen Arbeiten, sowie durch die Städte Berlin, Charlottenburg, Rixdorf, Schöneberg, Wilmersdorf, Potsdam, Spandau, Lichtenberg und Düsseldorf. Herausgegeben im Auftrage der Arbeitsausschüsse von Dr. Werner Hegemann, Generalsekretär der Städtebau-Ausstellungen in Berlin und Düsseldorf. 2 vols. Berlin: Wasmuth, 1911, 1913. (German)
- (with Elbert Peets) The American Vitruvius: An Architects' Handbook of Civic Art. New York: Architectural Book Publishing, 1922.
- Amerikanische Architektur und Stadtbaukunst: ein Überblick über den heutigen Stand der amerikanischen Baukunst in ihrer Beziehung zum Städtebau. Berlin: Wasmuth, 1925. (German)
- Das steinerne Berlin: Geschichte der grössten Mietkasernenstadt der Welt. Berlin: Kiepenhauer, 1930. (German)
- Entlarvte Geschichte. Aus Nacht zum Licht. Von Arminius bis Hitler. Leipzig: Hegner, 1933. (German)
- City planning, Housing. 3 vols. Vols. 2 and 3 with William W. Forster and Robert C. Weinberg. New York: Architectural Book Publishing, 1936–38. OCLC 837328
- Werner Oechslin, "Between America and Germany: Werner Hegemann's Approach to Urban Planning," in Berlin/New York: Like and Unlike: Essays on Architecture and Art from 1870 to the Present, ed. Josef Paul Kleihues and Christina Rathgeber, New York: Rizzoli, 1993, ISBN 0-8478-1657-5, pp. 281–95, p. 287.
- Christiane Crasemann Collins, Werner Hegemann and the Search for Universal Urbanism, New York: Norton, 2005, ISBN 0-393-73156-1, p. 35.
- "Die Städtebau-Ausstellung und ihre Lehren," Die Woche; Der Städtebau nach den Ergebnissen der allgemeinen Städtebau-Ausstellung in Berlin, 1911, 1913. Collins, p. 51, p. 373, note 45; p. 375, note 72.
- Edward Marshall, "VASTER SKYSCRAPERS INEVITABLE, SAYS GERMAN EXPERT; Dr. Werner Hegemann, One Of the World's Greatest Authorities on City Planning, Says Our Present High Buildings Mean Intolerable Congestion and Will Be Succeeded by Structures Ten Times as Great but More Widely Separated – Faults of Subways Pointed Out," New York Times magazine, April 6, 1913 (pdf) retrieved December 18, 2010.
- Collins, p. 20.
- "Biographical résumé of Elbert Peets," On the Art of Designing Cities: Selected Essays of Elbert Peets, Ed. Paul David Spreiregen, Cambridge, Massachusetts: MIT, 1966, OCLC 604141820, p. 226.
- Oechslin, p. 292 (translation there).
- Collins, pp. 306, 316.
- Collins, p. 321.
- Collins, p. 335.
- Collins, pp. 362, 363.
- Collins, p. p. 352.
- Oechslin, p. 291, referring to it as City/Planning/Housing.
- Oechsler, p. 290.
- Oechslin, p. 292; p. 295, note 119.
- Oechslin, p. 291, quoting in translation from "Kritik des Grosstadt-Sanierungs-Planes Le Corbusiers," Der Städtebau (1927) p. 70.
- Caroline Flick. Werner Hegemann (1881–1936): Stadtplanung, Architektur, Politik: ein Arbeitsleben in Europa und den USA. Munich: Saur, 2005 (German)