Born in Berlin in 1923, John Weitz (born Hans Werner) completed his education in London at the Hall School and at St. Paul's School, after which he apprenticed with fashion designer Edward Molyneux. Weitz's parents, assimilated German Jews, immigrated to the United States in response to the rise of National Socialism. Weitz was able to re-join his family in the United States after a stay in Shanghai, a city in which many German and Austrian Jewish refugees lived during the late 1930s. Weitz became a naturalized citizen of the United States in 1943 and enlisted in the U.S. Armed Forces that year. He served through 1945, returning to Germany as an American soldier. Over four decades later, the Federal Republic of Germany honored him with a First Class Order of Merit for his wartime contributions.

In the late 1940s, Weitz began designing women's apparel and was noticed by Dorothy Shaver of Lord & Taylor, thus beginning a multi-decade relationship with the retailer. Weitz initially specialized in women's sportswear and was often featured in print advertisements with sports cars, a serious hobby that he would cultivate and employ extensively in fashion styling and marketing (in 1979, he designed his own car, the X600, and used Bloomingdale's store windows as the site of its first public display). Weitz also made numerous in-store appearances to promote his clothing, serving as commentator for his own fashion shows, an uncommon idea at the time. He would continue this practice into the 1980s.

By the mid-1960s, Weitz had primarily shifted his attention to menswear and is recognized today as one of the first American menswear designers. He received a Special Menswear Coty Award in 1974. Weitz also frequently expressed his opinions regarding how American men should dress, groom, and conduct themselves, writing articles, being interviewed by style journalists, and appearing on television and radio programs to promote his mantra of functionality, modernity, and masculinity. Cosmopolitanism played a large role in the marketing of Weitz's menswear, with Weitz proposing that a modern man should be at home anywhere in the world. Weitz returned to designing women's apparel in 1979 with a much-publicized women's collection. He would design both men's and women's clothing for the rest of his career as a fashion designer.

A savvy businessman, Weitz was one of the earliest American designers to enter into licensing agreements. His name, likeness, and signature were associated with numerous accessories and a wide range of men's apparel, making him a multi-millionaire. In 1954, Weitz left Lord & Taylor to found an independent company, John Weitz Designs, Inc., although his menswear continued to be sold through Lord & Taylor's Man's Shops.

In 1968, Weitz entered into a major licensing deal with Teijin, which at that time was a fabric manufacturer. Teijin sold John Weitz Design fashions and home furnishings to Japanese consumers through the Daimaru department store chain, a venture that lasted several decades. Weitz traveled regularly to Japan, making in-store appearances throughout the country. As in American campaigns, Japanese print and television advertising relied heavily on Weitz's likeness and represented him as an "all-American" man. By 1981, the Japanese market represented approximately 30% of Weitz's retail sales ("Japan Ready Market for U.S. Clothing," DNR, June 29, 1981). Weitz also entered into licensing agreements with department stores in Mexico and in the U.K.

In 1970, Weitz published a best-selling novel about the fashion world, The Value of Nothing (his first book  Sports Clothes for Sports Cars, appeared in 1958). Four years later, he released an advice book for men,  Man in Charge: The Executive's Guide to Grooming, Manners, and Travel. In 1982, he turned his attention to historical fiction, writing about a young man in Nazi-era Germany in  Friends in High Places. This was followed by two works of non-fiction in the 1990s,  Hitler's Banker and  Hitler's Diplomat. In addition to book-length works, Weitz wrote extensively for a variety of publications as a columnist and contributor. Frequent topics include fashion and style, cars and driving, New York City, and Nazi Germany.

John Weitz died in 2002 in Bridgehampton, Long Island at the age of 79. His is survived by his third wife, actress Susan Kohner, and four children.

The papers are of a professional nature, either created and received by John Weitz in his capacity as a designer, artist, or author, or by John Weitz Designs employees Helen Berkowitz, Barbara Khoury, Andrea Peterson, and Michael Wynne. Files chronicle the relationship between fashion designers, textile manufacturers, and the garment industry. In addition to men's, women's, and children's clothing, the papers also include designs for a sports car and a yacht. Weitz's roles as author and artist are also documented, though not extensively.

In addition to fashion and product design, the papers evince a range of fashion merchandising practices, from fashion illustration and photography, to advertising copy and marketing campaigns represented by press kits, publications, and highly choreographed fashion shows. Roughly five decades of fashion marketing materials are present. The John Weitz papers also provide a window into a vanished world of family-owned, regional retailers and localized fashion merchandising. Because Weitz was one of the first American designers to enter the post-war Japanese retail market, the papers are noteworthy for including documentation on promoting American fashions to Japanese consumers.

Advertisements for John Weitz Designs were innovative in their use of celebrity and lifestyle marketing. They also frequently exploit anxieties regarding evolving gender roles, such as humorous campaigns for women's office attire and seasonal collections with suggestive titles like "Big Man." Weitz, along with his longtime advertising agency, C. J. Herrick Associates, recognized the increasing sophistication of American consumers, developing brand-focused advertising featuring John Weitz's face, name, and logo rather than products. In 1979, Weitz became the first designer to advertise on New York City municipal buses ( WWD, Janaury 31, 1979, p. 27). Another campaign involved excerpts of mock stories (written by Weitz) in which John Weitz Designs' products are mentioned by name within the context of the story. The increasingly self-referential advertising generated much publicity on its own. The papers include extensive publicity materials for John Weitz Designs' apparel and licensed products.

The papers are organized into five series by function, and arranged alphabetically. Fashion shows and press kits in the Publicity series and some scrapbooks are arranged chronologically because of repetition in or absence of original folder titles.

File titles have been changed or altered when the original title was absent, unclear, repetitive, or inaccurately labeled.

The Fashion Institute of Technology holds an oral history recording conducted with John Weitz and video recordings of his fashion shows.