Stephanie Kwolek was born on July 31, 1923, in New Kensington, Pennsylvania. Her father worked in the Pittsburgh steel industry but was a naturalist at heart, while her mother was at first a homemaker, and then a career woman by necessity. From her father, Kwolek learned a great deal about nature. Her mother gave her a love of sewing and fabrics. Before her love for chemistry and medicine developed, Kwolek thought she might become a fashion designer. Kwolek's father died when she was ten-years-old.

Kwolek attended the women's college, Margaret Morrison Carnegie College of Carnegie Institute of Technology (now Carnegie-Mellon University). She graduated in 1946 with a BS in Chemistry. She did not have the funds to attend medical school; instead she took a job at Dupont's textile fabrics laboratory as a chemist in Buffalo, New York. When Dupont's Pioneering Research Laboratory opened in 1950 in Wilmington, Delaware, Kwolek moved her work there. She was one of the few female chemists working at the end of World War II. The first director of the lab was W. Hale Church. Church was the person who interviewed Kwolek and offered her a job at Dupont in 1946. With his support, Kwolek had a great deal of success at Dupont.

Kwolek's work at Dupont was with polymers. She worked polymer condensation, creating long chains of molecules at low temperatures. Although she obtained 28 patents throughout her career, her most important invention came with her work in the intermediates used in low-temperature polymerization. The result of her work was finding an aramid polymer. The solution was first rejected for spinning because it was cloudy and thought to damage equipment. After much insisting, Kwolek finally spun the solution and the results were strong, stiff fibers.

The new crystalline polymers created a fiber five times stronger per ounce than steel and about half the density of fiberglass. The commercial version of this fiber was Kevlar in 1971. Kevlar has many important applications such as bullet proof vests, radial tires and brake pads, racing sails, fiber optic cable, water-, air- and spacecraft shells, mooring and suspension bridge cables, skis, safety helmets, and hiking and camping gear. The use of Kevlar has saved thousands of lives and generates hundreds of millions of dollars per year worldwide in sales.

For her invention of Kevlar and her 40-year career at Dupont, Kwolek earned many awards, including the Kilby Award and National Medal of Technology in 1996. Kwolek was only the fourth woman to be inducted into the Inventors Hall of Fame in 1994 out of its 113 members. In 1997, Kwolek received the Perkin Medal from the American Section of the Society of Chemical Industry. Kwolek also won the 1999 Lemelson-MIT Lifetime Achievement Award. She retired from Dupont in 1986.

After her retirement, Kwolek spent time on various hobbies, such as sewing and gardening. She gave many lectures on her life and inventions and tutored high school students in chemistry. Kwolek passed away at the age of 90 on June 18, 2014, in Wilmington, Delaware. On the day of her death, Dupont announced the sale of the 1 millionth bullet-proof vest made of Kevlar.

In addition to her work with students and her selection to numerous Halls of Fame, Kwolek will be remembered in children's literature. According to the New York Times, her story, told in 48 pages, became one in a series of children's books about inventors and innovative ideas in 2013. The book, by Edwin Brit Wyckoff, is titled The Woman Who Invented the Thread That Stops the Bullets: The Genius of Stephanie Kwolek."