Paris was the most important artistic center in Europe at this time, and many key developments in the formation of Art Nouveau took place there. From the mid-1890s, works by emerging young designers were exhibited at Bing's gallery L'Art Nouveau. And the city hosted the World's Fair of 1900, which also helped to bring Art Nouveau to center stage. At this time Hector Guimard, perhaps the most prominent Parisian Art Nouveau designer, was commissioned to design entrances for the city's new subway system. With their organic and tense linear style and use of cast iron for both structural and decorative purposes, they are among the most famous icons of the Art Nouveau style. Artist Henri de Toulouse-Lautrec, also associated with Art Nouveau circles, was particularly active in the graphic arts. His posters for café-concerts such as the Divan Japonais reveal the influence of Japanese art in their strong outlines and bold, flat patterns.

Brussels was also at the center of the development of Art Nouveau: many of its earliest and most important creations were either made or exhibited in the city. At this time Brussels enjoyed a new prosperity from the wealth it had gained during the Industrial Revolution and Belgium's colonial expansion in Africa. The city underwent great change, and Art Nouveau became the style most representative of the transformation. In 1893 Victor Horta, the leading architect-designer in Brussels, designed Tassel House, the first fully developed example of architecture in the Art Nouveau style. Other influential Belgian designers included Henry van de Velde and Gustave Serrurier-Bovy. Both created furniture that blends an emphasis on structure with lyrical curvilinear elements abstracted from nature.

Although Art Nouveau was not generally embraced in England, the style developed in exciting new directions in the Scottish city of Glasgow. Elements of vigorous industrialism, modernity, and ethnic pride all played their part in the particular strain of Art Nouveau that emerged there. The work of Charles Rennie Mackintosh and other artists and designers of the Glasgow school is typified by a linear restraint. Inspired by Japanese art, they introduced into their designs a strict rectilinear geometry, along with stylized plant and figurative forms. Among Mackintosh's most important patrons was Miss Cranston, a Glasgow tearoom owner for whom he designed several interiors. The Ladies' Luncheon Room at Ingram Street typically integrated architecture, furniture design, and decorative glasswork.

Art Nouveau in Vienna was known as the Secession style after seminal Viennese artist Gustav Klimt led the city's progressive artists and designers into forming the Vienna Secession group in 1897. Members of the group broke free from the conventions and constraints of existing Viennese art establishments by breaking down the barriers between art, design, and craft. Influenced by the geometry of the Glasgow school and the simplicity of Japanese design, the work of the Viennese designers is characterized by a restrained linearity and elegance. In 1903 Josef Hoffmann and Koloman Moser, both members of the Secession group, established the Wiener Werkstätte (Vienna Workshops), which emphasized the important role of craftsmanship and an integrated approach to the design of interiors.

Jugendstil was the name given to Art Nouveau in Germany. The term came from the title of the Munich periodical Die Jugend (The Youth), established in 1896. In Munich, as elsewhere, Art Nouveau was a complex style that found expression in a number of different approaches. Otto Eckmann, one of the leading and most prolific artists of the new generation, designed all manner of objects, from textiles and furniture to ceramics and metalware, which reflect the importance attributed to the applied arts at that time. His tapestry Five Swans became an icon of the Munich Jugendstil: its celebration and abstraction of natural forms, along with its sinuous lines and manipulations of space, define its modernity. In 1898 leading Munich designers Richard Riemerschmid and Hermann Obrist formed the Vereinigte Werkstätten für Kunst im Handwerk (United Workshops for Art in Handicraft), which promoted the production of modern design. Riemerschmid's work illustrates the new priorities of Munich artists, reflecting both their obsession with nature and insistence on rational, efficient design.

In Italy, Art Nouveau was known as stile floreale, a name derived from the curving, floral designs favored by the artists and designers there, or stile Liberty, after the famous store in London, which sold the work of modern designers. Turin was a leader in Italy's economic growth at that time and an important center for the development of Italian Art Nouveau. In 1902, it hosted the Prima Esposizione Internazionale d'Arte Decorativa Moderna, the most ambitious display of international decorative art ever attempted. Leading Turinese furniture designers Vittorio Valabrega and Agostino Lauro both participated in the exhibition, as did the Milanese designer Carlo Bugatti. Lauro exhibited furniture from a room that he had designed for a villa belonging to a textile manufacturer in the Piedmontese town of Sordevolo. The room is a prime example of the Art Nouveau principle of Gesamtkunstwerk, combining architecture, furnishings, and decoration into a harmonious whole.

In the Art Nouveau period, New York became one of the world's great economic and cultural centers. The patronage of an outstanding generation of industrialists and financiers led to the creation of public museums, libraries, and grand private mansions. In this environment of confidence and wealth, American artists and designers developed their own version of the new art. The most prominent of these was Louis Comfort Tiffany, one of the greatest glass artists and manufacturers of his time. He pioneered a wide range of visually distinctive, highly advanced glass technologies, creating key masterpieces in the Art Nouveau style. His sources of inspiration ranged from excavated Roman glass and medieval stained glass, to exotic Japanese, Chinese, and Islamic forms. Equally important was his scrutiny of plants and insects, which he transformed into colorful and sensual celebrations of the natural world. Included in the inaugural exhibition of Bing's Paris gallery L'Art Nouveau, Tiffany's creations were much admired by European artists and patrons.

After the Chicago fire of 1871, architects and structural engineers flocked there. As they rebuilt the city's streets and structures, they developed a new form of architecture that was appropriate for the modern age. Among the principal architects working in Chicago was Louis Sullivan, one of the few American architects to find a place in the international Art Nouveau movement. His skyscrapers constructed around steel frames reflect the technological advancements of the age. Their exteriors were decorated with intricate ornaments inspired by forms in nature and by Celtic art. With these designs, Sullivan brought elements of nature into the urban landscape. His chief designer, George Grant Elmslie, created similar ornaments, such as the teller wicket for the National Farmers' Bank at Owatonna. The designs of Frank Lloyd Wright, a disciple of Louis Sullivan, were also informed by the natural world, but Wright developed a very different aesthetic. Rigid and rectilinear, his buildings, furniture, and stained glass were much influenced by the art and architecture of Japan. The dining room furniture that he created for the Frederick C. Robie House in 1907 reflects his fascination with Japanese design.