Dayana beat 27 other candidates to win Miss Venezuela 2007 on September 13, 2007, and became only the second woman representing the Amazonas state to win (the first being Carolina Izsak in 1991). She was crowned Miss Universe 2008 at the pageant in the Crown Convention Center, Nha Trang, Vietnam on July 13, 2008.Mendoza became the first winner of the pageant from Venezuela since Miss Universe 1996's winner Alicia Machado, thus making her the first Venezuelan Miss Universe in the 21st century.Miss Universe 2007 Riyo Mori crowned her with a tiara worth 120,000 U.S. dollars. Her prize package includes cash, a year contract promoting Miss Universe, world travel, a rent-free, prestigious New York City flat, luxury apartment and a gift bag stuffed with designer shoes, dresses and beauty products, a $100,000 stipend for a 2-year course at the New York Film Academy and free access to famous fashion houses and beauty parlors. Mendoza will spend her year-long reign traveling the world to lecture on humanitarian issues and to promote education regarding HIV/AIDS.As of March 2009, Mendoza as Miss Universe has traveled to Indonesia, Aruba, Singapore, Puerto Rico, Spain, Italy, France, Nicaragua, Ukraine, Czech Republic, Bahamas, Russia and Vietnam, in addition to numerous trips around the USA and her homecoming in Venezuela.