The pizza pie, which the pair claims is based on their mother's recipes, was originally sold at Roma's Pizza in the 1960s before Joe moved to Chicago and helped to found the current franchise. Giordano's is one of the most famous of Chicago's pizzerias, and its major competitors in the Chicago-style deep dish field are Pizzeria Uno, Nancy's, Gino's East, and Lou Malnati's while its thin crust pizza competes primarily with Home Run Inn, Connie's, Aurelio's and Rosati's. Along with Uno's and Gino's, Giordano's has been described as one of Chicago's "main pizza triumvirate". The Rough Guide to Chicago has written, "Although most pizza parlors offer deep-dish, the following places have perfected it: Pizzeria Uno, Lou Malnati's ..., and Giordano's.
They have 13 restaurants in Chicago, another 29 locations in the Chicago metropolitan area, and one in Rockford, Illinois. To try to bring authentic Chicago-style pizza to the heavily transient population of Florida, Giordano's has opened its first locations outside Illinois, with six stores opening in northern and central Florida. Early Florida locations were opened in Lake Buena Vista and Kissimmee. By October of 2007, Giordano's had opened stores in Port Richey, Brandon, and Tampa. Giordano's is very popular with soon-to-be-wed couples as a place to hold rehearsal dinners and engagement parties.