Steiner has contributed cartoons and other material to The New Yorker since 1979. His cartoon captioned 'On the internet nobody knows you're a dog' is one of the most reproduced cartoons from The New Yorker, and Steiner has earned over $50,000 from its reprinting. Steiner also is well known for his daily cartoons on contemporary events for the Washington Times, which he created for nearly 20 years, starting in 1983. One selection of these cartoons was published in 1994. For several years in the late 1990s and early 2000s he also made cartoons for The Weekly Standard.
Steiner has written four novels, all featuring a former CIA agent named Louis Morgon who has retired to the Loire Valley in France. Of his 2010 novel The Terrorist, The New York Times reviewer Marilyn Stasio wrote that "While it can't be said that any of [the plot] is the least bit plausible, Steiner presents us with a reassuring fantasy world in which rash youths bow to the wisdom of their elders, terrorists abort their missions out of compassion for their human targets and the innocent victims of egregious acts of cruelty find it in their hearts to forgive."