Cynthia Rowley (born 1959) is an American fashion designer. A native of Illinois, Rowley attended Barrington High School in Barrington, Illinois, graduating in 1976, and the School of the Art Institute of Chicago.

Her Cynthia Rowley Collection is sold in Cynthia Rowley boutiques in New York City, Los Angeles, East Hampton, and Chicago, in better department and specialty stores worldwide, and in over 50 Cynthia Rowley boutiques in Japan.

The Council of Fashion Designers of America honored Rowley with the New Fashion Talent Award and a nomination for the Perry Ellis Award for New Menswear Design Talent.

She is the co-author of the best-selling line of Swell books and co-creator of the Swell line home products. Her latest book, Slim: A Fantasy Memoir, was released in May 2007. Rowley has appeared as a judge on the reality television programs Project Runway and Design Star and has been a guest on The Today Show, Good Morning America, The Oprah Winfrey Show, and the Late Show with David Letterman, among other programs.

She was married to Tom Sullivan (deceased) in 1988, Sculptor Bill Keenan in 1996, and now writer Bill Powers in 2005. She has two children, Gigi Clementine (born 2005) and Kit Clementine (born 1999).

Illinois native Cynthia Rowley was seven when she designed her first dress and a senior at the School of the Art Institute of Chicago when she sold her first collection of eight pieces to some of New York's most prominent stores. Over the years, the Cynthia Rowley collection has grown to include menswear, jeans, shoes, eyewear, hosiery, umbrellas, handbags, small leather goods and a signature fragrance. There are Cynthia Rowley boutiques in New York, Los Angeles, Chicago and East Hampton, and many in Japan. The collection is also represented in better department and specialty stores both domestically and internationally. Cynthia's creative endeavors have proven to be award winning. The Council of Fashion Designers of America (CFDA) honored her with the prestigious New Fashion Talent Award. The CFDA recognized Cynthia again three seasons after introducing a complete menswear line with a nomination for the Perry Ellis Award for New Menswear Design Talent. A wide range of targeted media has helped Cynthia Rowley reach a large national and international audience. She has appeared on television in business profiles on CNN and CNBC. She has been featured on MTV, "Entertainment Tonight," VH1, "Life of Luxury," and E!. Cynthia has also appeared on the "Late Show with David Letterman," and is a frequent guest on national morning shows, including "Good Morning America," "The Today Show" and "The View." Editorial coverage includes features in print media such as Harper's Bazaar, W, Vogue, Elle, Glamour, and The New York Times. Lifestyle features showcasing the unique interior of her homes include Harper's Bazaar, In Style, Elle Décor, French Vogue and The New York Times. In 1999, Cynthia and her best friend, Ilene Rosenzweig, the former deputy style editor for The New York Times, co-authored the best-selling book, Swell: A Girl's Guide to the Good Life. The highly anticipated sequel, Home Swell Home, was released in 2002 and was followed by Swell Holiday in 2003. The next book in the series, an entertaining guide, The Swell Dressed Party, will hit bookshelves in spring 2005. Swell's popularity has brought many exciting spin-offs: a monthly column in Glamour, engagement calendars, mini-books, Swell-related television programs and products for the home.