Carpenter has been married to producer Sandy King since 1990. King produced a number of Carpenter's later feature films, including They Live, In the Mouth of Madness, Ghosts of Mars, and Escape from L.A. She also functioned as script supervisor for some of these films as well, such as Starman, Big Trouble in Little China and Prince of Darkness.
Carpenter is a Godzilla fan. He appeared in an episode of Animal Planet's Animal Icons titled "It Came from Japan."
In an interview Carpenter had said that he has been diagnosed with skin cancer several times and that he believes the reason for this was working on The Thing due to the sun's rays bouncing off the snow and onto his face.