Hahn was raised in rural Northern California, and grew up playing with a wardrobe of Barbie outfits meticulously crafted by her grandmother. Hahn sewed all her own clothes in elementary and high school. As a teenager, she apprenticed with a leather tailor, cutting patterns and working treadle sewing machines. She would pour over fashion magazines and sought out vintage suits and handmade sweaters at thrift shops as she continued to learn about fabric and detail. After a brief stint at the Fashion Institute of Technology in New York, Susan Hahn enrolled in the School of the Art Institute of Chicago, graduating with a BFA in 1984. In Chicago, she interned with fiber artist Anne Wilson, studied kimono forms and created fiber sculptures to accompany her choreography. "The installations were much better than my dances," she says. Hahn began sewing again and founded her first company,  SU-ZEN in 1984. The company developed a devoted clientele of women who were attracted to her unique fabrics, impeccable quality, and comfortable fit.  In 2002, after 18 years in business, Hahn closed SU-ZEN, moved to New York, and started a new line under her own name.

The new collection is smaller and features Hahn's true love- knitwear. The fall 2009 collection is comprised of cardigans and pullovers that range from tiny to oversized, all with homey hand stitched touches. "I made my first sweaters in 1984 by joining hand knit panels with fabric, so I guess I am going back to my roots with these".

Susan Hahn is married to designer Ian McPheely, and has three daughters who are, she says, "my inspiration and my best creations."