Irene Brady started writing and illustrating at age 19, and in 1969 her first book, America's Horses & Ponies was published. She has published eleven books and illustrated another fourteen. She has also illustrated for magazines such as Audubon and Ranger Rick Nature Magazine, painted interpretive panels for the Forest Service, and created brochures and displays for nature centers and museums.
In the 1970s and 1980s, Brady gave talks to elementary school children about writing and illustrating nature books. In the late 1980s, she was Scientific Illustrator at the National Fish & Wildlife Forensics Lab in Ashland, Oregon, designing the national logo, creating graphics, illustrating articles for the scientists, and making courtroom displays for the Exxon Valdez oil spill trial and others.
In the 1990s, Brady taught a course in scientific illustration at Southern Oregon University. She developed the course into a workshop, and finally a series of books on illustrating wildlife. She continues to sketch in the woods surrounding her home in Oregon.
