As a student of landscape architecture at Cornell University, Rapuano received the Rome Prize in 1927. He began his career with the Westchester County Park Commission concurrently going into private practice serving wealthy clients in New York and New Jersey. By 1933, he was supplementing his private practice by working at Madigan-Hyland, Engineers, and the Landscape Architecture practice of Gilmore D. Clarke. Rapuano formed a partnership with Clarke in 1939 and their firm, Clarke and Rapuano, completed a vast number of landscape architecture, city and campus planning, and transportation projects across the United States and abroad. Rapuano became an expert on highway design and his projects include portions of the Bronx River Parkway, Henry Hudson Parkway, and Garden State Parkway. This expertise was further established by his participation in preparing the report The Freeway in the City for the Federal Department of Transportation in 1968. Other New York City projects include the United Nations Headquarters and Central Park in Manhattan and Orchard Beach in The Bronx. He also completed projects in Tennessee, Pennsylvania, and Ohio, as well as the American Military Cemetery in Florence, Italy. Rapuano was Trustee and President of the American Academy in Rome and a Fellow of the American Society of Landscape Architects.