The first non-Anglo-Saxon film to take the top prize in Oscars history struck gold at the 84th Academy Awards ceremony, earning a total of five golden statuettes including best director.
Other awards came for best original score and best costume design.
"I am the happiest director in the world right now," Hazanavicius said as he accepted his directing prize.
Dujardin -- a 39-year-old already well liked at home for his work on stage and screen -- joins Simone Signoret, Claudette Colbert, Marion Cotillard and Juliette Binoche in the elite club of French Oscar-winning actors.
"I love your country," Dujardin told the Oscars audience as he took the stage for his acceptance speech, the latest of many awards shows at which he has triumphed over the last few months.
His poignant performance as George Valentin in Michel Hazanavicius' charming ode to the silent film era has already earned him a Cannes festival prize, a Golden Globe, a BAFTA and an independent Spirit film award.
Overall, the film took home five Oscars on Sunday including awards for best picture and best director Hazanavicius.
"I've already won. Just being here, with all of these actors, these artists, is already huge!" Dujardin said in the run-up to Sunday's Oscars ceremony, with a mix of modesty and candor that has seduced Hollywood.
Born in the suburbs of Paris in 1972, Dujardin discovered a talent for acting during his mandatory military service. He cut his teeth in the French capital's cafe-theaters, before launching a comedic acting troupe.
Luck struck in 1999 when he was chosen to star in the televised serial "Un gars et une fille" ("A Guy and a Girl") with Alexandra Lamy, who became his wife in 2009.
For four years, the pair charmed viewers on France 2 and gave Dujardin the launch pad he needed.
Movie producers snapped him up, and from 2002 to 2004, he starred in a series of comedies including "Toutes les filles sont folles" ("All Girls Are Crazy") and "Les cles de bagnole" ("The Car Keys").
His breakthrough came in 2005 with "Brice de Nice" ("The Brice Man"), a film about a surfer dude character he had created on stage a decade earlier. Some 4.3 million people saw the film, and Dujardin became a bankable star.
He took on more serious roles as a cop searching for his daughter's killer in "Contre-enquete" ("Counter-Investigation"), and as a writer visited by the incarnation of his cancer in "Le bruit des glacons" ("The Clink of Ice").
The turn towards dramatic films however did not dissuade Dujardin, known for his seductive smile, from taking on other comedic fare.
In 2006, he worked for the first time with Hazanavicius in the James Bond parody "OSS 117: Cairo, Nest of Spies," which spawned a sequel, "OSS 117: Lost in Rio."
An actor faithful to his directors, he also reconnected with "Brice" director James Huth for "Hellphone" in 2007 and "Lucky Luke" two years later.
Often compared to Jean-Paul Belmondo for his ability to bring to life Everyman characters with humour and panache, Dujardin shared the screen with the great French actor in 2009's "Un homme et son chien" ("A Man and His Dog").
After his Oscar win, most will assume that Dujardin will be tempted by the bright lights of Tinseltown.
But the actor -- whose English is still basic, at best -- said as he promoted his latest film, "Les infideles" ("The Players") that he did not intend to change course right away.
"I am not the one who will decide to launch a career in the United States. I am still a French actor, and I am going to carry on as I always have," he said -- days after signing with a major Hollywood talent agency.