Bündchen was born in the Brazilian town of Três de Maio and grew up in Horizontina, Rio Grande do Sul, to Vânia Nonnenmacher, a bank clerk pensioner, and Valdir Bündchen, a university teacher and writer. She has five sisters — Raquel, Graziela, Gabriela, Rafaela and her fraternal twin Patrícia, Gisele's junior by five minutes. Bündchen is Roman Catholic, speaks Portuguese as her native language and English as a second language.
She is from Southern Brazil, a region whose population is largely composed of Brazilians of German descent. Bündchen is of German ancestry from both sides of her family, which is integrated in Brazilian society for many generations: her great-great-grandparents immigrated to Brazil from Germany. In regards to her ethnic background, Bündchen said:
Originally, Bündchen wanted to be a professional volleyball player and considered playing for the Brazilian team, Sogipa. While in school, Bündchen was so thin that her friends used to call her "Olívia Palito" (Portuguese for Olive Oyl, Popeye's skinny girlfriend) and "Saracura" (a type of Brazilian shorebird).
In 1993, a then-13-year-old Bündchen joined a modeling course with her sisters Patrícia and Gabriela at her mother's insistence. The following year, Bündchen went to São Paulo on a school excursion to give them an opportunity to walk in a big city. In a shopping mall, while eating a Big Mac with her friends, Bündchen was discovered by a modeling agency. She was subsequently selected for a national contest, Elite Look of the Year, in which she placed second — Claudia Menezes, from Bahia, took first place. Bündchen placed fourth in the world contest, held in Ibiza, Spain. In 1996, Bündchen moved to New York City to begin her modeling career, debuting at Fashion Week.
Her debut on the cover of the July 1999 issue of Vogue magazine, and the accompanying editorial entitled "The Return of the Sexy Model", is widely viewed[citation needed] as marking the end of the fashion's "heroin chic" era. She graced the cover again in November and December of that year. She won the VH1/Vogue Model of the Year for 1999, and a January 2000 cover gave her the rare honor of three consecutive Vogue covers. In 2000, she became the fourth model to appear on the cover of the music magazine Rolling Stone, when she was named "the most beautiful girl in the world." Bündchen has been on the covers of many top fashion magazines including W, Harper's Bazaar, ELLE, Allure, international editions of Vogue, as well as style and lifestyle publications such as i-D, The Face, Arena, Citizen K, Flair, GQ, Esquire, and Marie Claire.[7] She has been featured both in the Pirelli Calendar 2001 and 2006 and in broader market publications such as Time, Vanity Fair, Forbes, Newsweek and Veja, totaling more than 500 magazine covers throughout the world.
Bündchen consistently works with acclaimed photographers such as Mario Testino, Steven Meisel, Nick Knight, Mert and Marcus, Rankin, Annie Leibovitz, Karl Lagerfeld, Peter Lindbergh, David LaChapelle, Mario Sorrenti and Patrick Demarchelier, and with renowned directors such as Jean Baptiste Mondino and Bruno Aveillan.
Claudia Schiffer said: "Supermodels, like we once were, don't exist any more" and reckoned that Gisele Bündchen was the only one close to earning the supermodel title.
Naomi Campbell said: "Models need to earn their stripes - I just think the term is used a little too loosely. Kate Moss is obviously a supermodel but, after Gisele, I don’t think there’s been one."
On August 26, 2008, the New York Daily News, in a list, named Bündchen the fourth-most-powerful person in the fashion world.