Born Iris Barrel in Astoria, Queens, New York, Apfel is the only child of Samuel Barrel, whose family owned a glass-and-mirror business, and his Russian-born wife, Sadye, who owned a fashion boutique. Both were Jewish. 
She studied art history at New York University and attended art school at the University of Wisconsin. As a young woman, Apfel worked for Women's Wear Daily and for interior designer Elinor Johnson. She also was an assistant to illustrator Robert Goodman.
In 1948, she married Carl Apfel. Two years later, they launched the textile firm Old World Weavers and ran it until they retired in 1992. Through their business, the couple began traveling all over the world where she began buying pieces of non-Western, artisanal clothes. These clothes were the ones she started wearing to the high-society parties of their clients. From 1950 to 1992, Iris Apfel took part in several design restoration projects, including work at the White House for nine presidents: Truman, Eisenhower, Kennedy, Johnson, Nixon, Ford, Carter, Reagan, and Clinton.
Apfel's husband of 67 years, Carl Apfel, died in August 2015, just three days shy of his 101st birthday.
On September 13, 2005, The Costume Institute, at The Metropolitan Museum of Art, in New York City premiered an exhibition about Iris Apfel's style entitled Rara Avis (Rare Bird): The Irreverent Iris Apfel. The exhibition's upbeat success, organized by Stéphane Houy-Towner, prompted an initial traveling version of the exhibit at the Norton Museum of Art in West Palm Beach, Florida, the Nassau County Museum of Art in Roslyn Harbor, New York, and later at the Peabody Essex Museum in Salem, Massachusetts.
The Museum of Lifestyle & Fashion History in Boynton Beach, Florida is in the conceptual phase of designing a building which will house a dedicated gallery of Apfel's clothes, accessories and furnishings.
Apfel is the star of a documentary by Albert Maysles, called Iris. It premiered at the New York Film Festival in October 2014, and was subsequently acquired by Magnolia Pictures for US theatrical distribution in 2015.
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- Cartner-Morley, Jess; Mirren, Helen; Huffington, Arianna; Amos, Valerie (28 March 2013). "The 50 Best-dressed over 50s". The Guardian (London). Text "http://www.theguardian.com/fashion/gallery/2013/mar/29/50-best-dressed-over-50s" ignored (help)
- Museumsusa.org on Norton Museum of Art exhibition
- Warburton, Sophie (26 August 2011). "Victoria's Secret News". The Daily Telegraph (London).
- "Magnolia Pictures Acquires 'Iris,' Albert Maysles' NYFF Documentary". 24 October 2014.