With Martin Greenberg, Kyle founded Gnome Press in 1948. He has written two pictorial histories of science fiction (A Pictorial History of Science Fiction and The Illustrated Book of Science Fiction Ideas and Dreams) and three licensed novels set in the Lensman universe (The Dragon Lensman, Lensman from Rigel and Z-Lensman). He appeared with Paul Levinson, Greg Bear and many others on the History Channel's 2002 documentary, Fantastic Voyage: Evolution of Science Fiction.
He attended the first Worldcon, and both wrote and printed the "Yellow Pamphlet" condemning the organizers. Kyle was also Fan Guest of Honor at ConStellation, the 41st World Science Fiction Convention, in 1983. In addition, he has written hundreds of articles for various fanzines, including regular articles for Richard and Nicki Lynch's Mimosa.