Mucha moved to Paris in 1887, and continued his studies at Académie Julian and Académie Colarossi while also producing magazine and advertising illustrations. Around Christmas 1894, Mucha happened to drop into a print shop where there was a sudden and unexpected demand for a new poster to advertise a play starring Sarah Bernhardt, the most famous actress in Paris, at the Théâtre de la Renaissance. Mucha volunteered to produce a lithographed poster within two weeks, and on 1 January 1895, the advertisement for Gismonda appeared on the streets of the city. It was an overnight sensation and announced the new artistic style and its creator to the citizens of Paris.. Bernhardt was so satisfied with the success of that first poster that she entered into a 6 years contract with Mucha.
Mucha produced a flurry of paintings, posters, advertisements, and book illustrations, as well as designs for jewellery, carpets, wallpaper, and theatre sets in what was initially called the Mucha Style but became know as Art Nouveau. Mucha's works frequently featured beautiful healthy young women in flowing vaguely Neoclassical looking robes, often surrounded by lush flowers which sometimes formed haloes behind the women's heads. In contrast with contemporary poster makers he used paler pastel colors. The 1900 Universal Exhibition in Paris diffused the "Mucha style" internationally. He decorated the Bosnia and Herzegovina Pavilion and collaborated in the Austrian one. His Art Nouveau style was often imitated. However, this was a style that Mucha attempted to distance himself from throughout his life; he insisted always that, rather than adhering to any fashionable stylistic form, his paintings came purely from within and Czech art. He declared that art existed only to communicate a spiritual message, and nothing more; hence his frustration at the fame he gained through commercial art, when he wanted always to concentrate on more lofty projects that would ennoble art and his birthplace.
Mucha married Maruška (Marie/Maria) Chytilová on June 10, 1906, in Prague. The couple visited the U.S. from 1906 to 1910, when their daughter, Jaroslava, was born in New York City. There he expected to earn money to fund his nationalistic projects to demonstrate to Czechs that he had not "sold out". He was supported by millionaire Charles R. Crane, who applied his fortune to promote revolutions, and after meeting Thomas Masaryk, Slavic nationalism. The family then returned to the Czech lands and settled in Prague, where he decorated the Theater of Fine Arts, contributed the murals in the Mayor's Office at the Municipal House, and other landmarks of the city. When Czechoslovakia won its independence after World War I, Mucha designed the new postage stamps, banknotes, and other government documents for the new state.
He spent many years working on what he considered his fine art masterpiece, The Slav Epic (Slovanská epopej), a series of twenty huge paintings depicting the history of the Czech and the Slavic peoples in general, bestowed to the city of Prague in 1928. He had dreamt of completing a series such as this, a celebration of Slavic history, since he was young. Since 1963 the series has been on display in the castle at Moravsky Krumlov.
By the time of his death, Mucha's style was considered outdated. However, his son, author Jiří Mucha, devoted much of his life to writing about him and bringing attention to his art. Interest in Mucha's distinctive style experienced a strong revival in the 1960s (with a general interest in Art Nouveau) and is particularly evident in the psychedelic posters of Hapshash and the Coloured Coat, the collective name for two British artists, Michael English and Nigel Waymouth, who designed posters for groups such as Pink Floyd and The Incredible String Band.
In his own country, the new authorities were not interested in Mucha. His Slav Epic was rolled and stored for twenty-five years before being shown in Moravsky Krumlov and only recently has a Mucha museum appeared in Prague, run by his grandson.
It has continued to experience periodic revivals of interest for illustrators and artists. It is a strong acknowledged influence for Stuckist painter Paul Harvey whose subjects have included Madonna and whose work was used to promote The Stuckists Punk Victorian show at the Walker Art Gallery during the 2004 Liverpool Biennial. Sailor Moon released a series of official posters depicting five of the main characters mimicking Mucha's style. Comic book artist and current Marvel Comics Editor in Chief Joe Quesada also borrowed heavily from Mucha's techniques for a series of covers, posters, and prints. Deathgrind band Soilent Green used a picture by Mucha for the cover of their album Sewn Mouth Secrets.
One of Mucha's paintings, Quo Vadis or alternately Petronius and Eunice, was the subject of a legal dispute in 1986. The judgment handed down by Richard Posner describes parts of Mucha's life and work biographically.
Among his many other accomplishments, Mucha was also the founder of Czech Freemasonry.