DeForest was raised in Pittsford, New York. He studied freehand and mechanical drawing at Taylor’s Business College and Mechanics Institute (now the Rochester Institute of Technology). In 1896, while still a student, he was hired by landscape architect William Parce to be a draftsman. After completing his studies in 1897, he joined the landscape architecture firm Olmsted, Olmsted & Eliot in Brookline, Massachusetts. After a year, he returned to Rochester to become a partner in the firm Parce & DeForest, Landscape Architects. In that role DeForest helped design the General Electric Plot housing development and Parkview Cemetery, both in Schenectady, New York. In 1899 he returned to work for Olmsted, Olmsted & Eliot for a year before once again rejoining Parce in Rochester. In 1902 DeForest opened his own practice. His projects largely comprised private estates, in addition to cemeteries, housing developments, campuses, and factory grounds. Among his better-known projects are the estates of Harvey Firestone in Akron, Ohio, and George Eastman in Rochester. His relationship with Firestone lasted from 1911 until 1938 and included not only the design of Firestone’s Harbel Manor estate, but also Firestone Park, a 500-acre housing development for Firestone Company employees in Akron. He also designed Firestone Recreational Park and laid out additions to the Columbiana Cemetery, both in Firestone’s hometown of Columbiana, Ohio. In 1920 DeForest served as an advisor to the Akron Planning Commission. He designed the Rochester estate of newspaper editor Horatio Warner, returning to the project throughout the 1920s and 1930s. The estate’s castle and sunken gardens were added to Highland Park in 1951. DeForest was named a Fellow of the American Society of Landscape Architects in 1908 and was an active member within the society, serving as vice president and secretary. He died at the age of 81.