Slimbach was born in Evanston, Illinois in 1956. Shortly after, he moved to Southern California where he spent his childhood and his youth. After leaving college he developed an interest in graphic design and typefaces while running a small screen printshop for manufacturing posters and greeting cards. This work brought him into contact with Autologic Incorporated in Newbury Park, California. After training from 1983 to 1985, Slimbach worked as a type designer with Autologic Incorporation, where Sumner Stone also worked for a short time. There he received further training, not just as a type designer but also as a calligrapher. Slimbach was then self-employed for two years and developed the two typefaces ITC Slimbach and ITC Giovanni for the International Typeface Corporation in New York.
In 1987 he joined Adobe Systems. Since then, he has concentrated primarily on designing typefaces for digital technology, drawing inspiration from classical sources. He has developed many new fonts for the Adobe Originals program. His time at Adobe Systems in California has seen the production of, among others, the Utopia (1988), Adobe Garamond (1989), Minion (1990) and Poetica (1992) font families. In 1991, he received the Charles Peignot Award from the Association Typographique Internationale for excellence in type design. More recently, Slimbach's own roman script calligraphy formed the basis for his typeface Brioso.
Since 2000, the rate of Slimbach's new typefaces has slowed, as he has taken advantage of the new linguistic and typographic capabilities offered by the OpenType format. Where in the 1990s a given typeface design might be instantiated in one or two fonts, with 200-500 glyphs, a typical new Slimbach work post-2000 has 1500-3000 glyphs.
In 2004, Adobe released Garamond Premier Pro, a new take on the Garamond designs, which Slimbach had been working on for 15 years, since he first completed Adobe Garamond in 1989.
Slimbach has notable skills in several fields other than type design: he went to college on a gymnastics scholarship, and he is an accomplished calligrapher and photographer. His photographic work uses black & white film, and is mainly portraits that examine human foibles and idiosyncrasies.