Kerr had a long career in journalism and juvenile book illustration. He drew for The American Weekly for thirty years. In the 1940s he was a staff artist for The New York Journal, where he illustrated editorials by Arthur Brisbane. Simultaneously Kerr worked for Dell Comics, on characters ranging from Raggedy Ann and Andy to Santa Claus.
In book illustration, Kerr's most notable achievement may be his art for four books by Thornton W. Burgess — Old Mother West Wind (two sets of illustrations for two editions in 1910 and 1914), Mother West Wind's Children, Mother West Wind's Animal Friends, and Mother West Wind's Neighbors. Kerr also illustrated Mary Frances Blaisdell's Bunny Rabbit's Diary, George Ade's The Slim Princess, Curtis Dunham's The Golden Goblin and Bobbie in Bugabooland, and Roy Snell's Little White Fox and His Arctic Friends and An Eskimo Robinson Crusoe.