Leon Kelly was born in Yardley, PA. Close to his father growing up, Kelly's interest in art was sparked by his father's collection of paintings and sculptures. He was a student at the Pennsylvania Academy of the Fine Arts (PAFA). There he would have learned about European modernism and cubism from his teacher Earl Horter, from printed reproductions, from sensational exhibitions like the influential Armory Show of 1913 or the works in Alfred Stieglitz’s 291 gallery, as well as through his studies under Arthur B Carles. Upon his graduation from PAFA in 1924, Kelly was awarded a traveling scholarship, which he used to move to Paris, where he stayed until 1930. From the early 1940s until his death in 1982, Kelly lived on Long Beach Island, where he befriended the scientists Albert and Lorraine Kligman, .