Millman studied at the University at Albany, SUNY for her undergraduate Bachelor of Arts degree. She majored in English with a minor in Russian literature, graduating in 1983. During her years there, she wrote for the student newspaper, which is where she credits discovering her interest in design.

In 1993, Millman became the off-staff creative director of HOT 97 in New York City, where she worked with Emmis Broadcasting general manager Judy Ellis and Promotion Director Rocco Macri to turn the dance music radio station into a hip-hop radio station. Millman created the HOT 97 logo in 1994 and then redesigned it again in 1999.

From 1995 to 2016, Millman was the president of the Design Division, and chief marketing officer at Sterling Brands based in New York City, where she worked with brands including Pepsi, Gillette, Colgate, Kimberly-Clark, Nestlé, and the Campbell Soup Company. She worked on the redesign of Burger King, merchandising for Star Wars, and the positioning and branding of the NO MORE movement.

She has served as the editorial & creative director of Print since 2002. In 2005, Millman left HOT 97 and founded Design Matters, a design podcast where she frequently interviews designers, educators, authors, and thinkers. Guests have included Massimo Vignelli, Steven Heller, Marian Bantjes, Tina Roth Eisenberg, and Stefan Sagmeister, Milton Glaser, Malcolm Gladwell, Dan Pink, Barbara Kruger, and Seth Godin, among others.

In 2008, Millman and her partners sold Sterling Brands to Omnicon. Millman was a writer for Armin Vit’s design blog Speak Up from 2003 until it ceased publication in 2009.

In 2009, Millman and Steven Heller founded a graduate program in branding at the School of Visual Arts in New York City. She serves as chair of the program. The school’s inaugural class wrote and designed the Rockport book Brand Bible: The Complete Guide to Building, Designing and Sustaining Brands, and in 2013 the students designed and created branding for the Museum of Modern Art’s retail program, Destination: New York.

Millman became the President Emeritus of American Institute of Graphic Arts (AIGA) in 2014, one of five women to hold the position in the organization’s 100-year history. She is a former board member and treasurer of the New York Chapter.

In 2014, she received the Type Directors Club Certificate of Typographic Excellence for her entry in TDC61, ‘Austin Initiative for Graphic Awesomeness’ poster. Her book Self-Portrait As Your Traitor was awarded a Gold Mobius, a Print Typography Award, and a medal from the Art Directors Club.

In 2015, the School of Visual Arts began to reposition the Kappa Middle School in Harlem and in 2016, they rebranded Mariska Hargitay’s Joyful Heart Foundation. The class of 2017 redesigned the identity of the Performance Space 122 in New York City.

In September 2017, she curated a show for the Museum of Design in Atlanta titled Text Me: How We Live In Language, featuring artists and designers including Ed Ruscha, Jean-Michel Basquiat, Shepard Fairey, Neil Gaiman, Deborah Kass and Lesley Dill. Arts Atlanta called the show a bold first curation. Millman co-curated conferences such as HOW DESIGN LIVE, the 2017 AIGA National Conference. Since 2013 she has curated 30 Covers, 30 Days for National November Writing Month.

By 2017, Design Matters had passed the five million downloads per year mark. The podcast received a number of awards such as the Cooper Hewitt National Design Award, The People’s Design Award, and in 2015 iTunes named it one of the best podcasts of the year. It was recognized as a Webby Honoree in 2018.

Millman is married to author Roxane Gay. On July 9, 2020 Gay tweeted that they had already eloped but planned to have a proper ceremony officiated by Gloria Steinem in 2021.