Before Marie Antoinette arrived in France from Austria, she had been schooled in the nuances of galant spoken French and French fashions. She was introduced to Bertin in the summer of 1774.[{{Cite book |last=Campan |first=Jeanne-Louise Henriette |title=Mémoires de Madame Campan, Première Femme de Chambre de Marie-Antoinette |publisher=Mercure de France |year=1988 |editor-last=Chalon |editor-first=Jean |location=Paris |page=73 |editor-last2=Angulo |editor-first2=Carlos de}}] Marie Antoinette commissioned Bertin to make her robes for the Coronation of Louis XVI, which were reportedly so heavy that they had to be carried to Rheims from Paris on a stretcher.[{{Cite book |last=Fraser |first=Antonia |title=Marie Antoinette: The Journey |publisher=Weidenfeld & Nicolson |year=2001 |location=London |pages=158–159}}]
Marie Antoinette was so enamoured of her fashion merchant that she abolished the historic custom of dressing in public in a formal levée ceremony, choosing instead to be dressed in private by Bertin.[{{Cite book |last=Campan |first=Jeanne-Louise Henriette |title=Mémoires de Madame Campan, Première Femme de Chambre de Marie-Antoinette |publisher=Mercure de France |year=1988 |editor-last=Chalon |editor-first=Jean |location=Paris |page=76 |editor-last2=Angulo |editor-first2=Carlos de}}] Twice a week, Bertin would present her newest creations to the queen and spend hours discussing them. The queen adored her wardrobe and was passionate about every detail, and Bertin, as her milliner, became her confidante and friend. Her position as the designer to the queen also secured her role as the leading fashion designer of the French aristocracy and, as French fashion was the leader in Europe, the central figure of European fashion.
Called "Minister of Fashion" by her detractors, Bertin was the brains behind almost every new dress commissioned by the queen. Dresses and hair became Marie Antoinette's personal vehicles of expression, and Bertin clothed the queen from 1770 until her deposition in 1792.[{{Cite book |last=Weber |first=Caroline |title=Queen of fashion: what Marie Antoinette wore to the Revolution |date=2007 |publisher=Aurum |isbn=978-1-84513-205-7 |location=London}}] Bertin became a powerful figure at court, and she witnessed—and sometimes effected—profound changes in French society. Her large, ostentatious gowns ensured that their wearer occupied at least three times as much space as their male counterpart, thus making the woman a more imposing presence. Her creations also established France as the center of the fashion industry, and from then on, dresses made in Paris were sent to London, Venice, Vienna, Saint Petersburg and Constantinople. This inimitable Parisian elegance established the worldwide reputation of French couture.
In the mid-18th century, French women had begun to "pouf" (raise) their hair with pads and pomade and wore oversized luxurious gowns. Bertin used and exaggerated the leading modes of the day, and created poufs for Marie Antoinette with heights up to three feet. The pouf fashion reached such extremes that it became a period trademark, along with decorating the hair with ornaments and objects which showcased current events.[{{Cite book |last=Chrisman-Campbell |first=Kimberly |title=Fashion victims: dress at the court of Louis XVI and Marie-Antoinette |date=2015 |publisher=Yale University press |isbn=978-0-300-15438-2 |location=New Haven (Conn.) London}}] Working with Léonard Autié, the queen's hairdresser, Bertin created a coiffure that became the rage all over Europe: hair would be accessorized, stylized, cut into defining scenes, and modeled into shapes and objects—ranging from recent gossip to nativities to husbands' infidelities, to French naval vessels such as the Belle Poule, to the pouf aux insurgents in honor of the American Revolutionary War.[{{Cite book |last=Bashor |first=Will |title=Marie Antoinette's head: the royal hairdresser, the Queen, and the Revolution |date=2015 |publisher=Lyons Press |isbn=978-1-4930-0063-0 |location=Guilford}}] The queen's most famous coif was the "inoculation" pouf that she wore to publicize her success in persuading the king to be vaccinated against smallpox.
Clothing had long served in France as one of the most visible markers of social privilege and aristocratic status. Antoinette was known for wearing many of the new groundbreaking fashions. Bertin came up with the idea of the chemise à la Reine or robe “en Gaulle”, a more free-flowing gown, which was initially created for Marie-Antoinette and was one of her favorite silhouettes. The dress sparked a mini-revolution and became very popular from 1781 onwards. It was a gown made to be worn in private spaces and made of white cotton, gauze, or silk. It was straight, very low cut and it was fastened with a belt around the waist, lightly accentuating the female figure. Antoinette and Bertin popularized English-inspired, sporty fashion, inspired by equestrian fashion. All the dresses were made of expensive fabrics such as silk, velvet, and very rarely cotton. It took hard work and dedication to create such masterpieces.
Marie Antoinette also asked Bertin to dress dolls in the latest fashions as gifts for her sisters and her mother, the Empress Maria Theresa of Austria. Bertin's fashion dolls were called "Pandores," and were made of wax over jointed wood armatures or porcelain. There were small ones the size of a common toy doll, or large ones as big or half as big as a real person, petites Pandores and grandes Pandores. Fashion dolls as couriers of modes[See the cultural analysis of fashion dolls in Julie Park (2010), The Self and It: Novel Objects and Mimetic Subjects in Eighteenth-Century England: "The Fashion doll and the mimetic self" pp 103ff.] remained in vogue until the appearance of Fashion magazines.
With the queen's patronage, Bertin's name became synonymous with the sartorial elegance and excess of Versailles. Bertin's close relationship with the queen provided valuable background into the social and political significance of fashion at the French court. The frequent meetings between the queen and her couturière were met, however, with hostility from the poorer classes, given Bertin's high prices: her gowns and headdresses could easily cost twenty times what a skilled worker of the time earned in a year.{{Citation needed|date=November 2010}}
During Marie Antoinette's imprisonment, Bertin continued to receive orders from her former prized customer, for much smaller, almost negligible ribbons and simple alterations. She was to provide the former queen's mourning outfit following the execution of Louis XVI, recalling a dream that Marie Antoinette had had years before of her favorite milliner handing her ribbons that all turned to black.
