Chalker was born on December 17, 1944, in Baltimore, Maryland. He began writing for the amateur science fiction press while still in high school, and in 1960, he founded the Hugo-nominated amateur magazine Mirage. He started Mirage Press a year later, which turned into a prominent specialist publisher of science fiction and fantasy nonfiction and reference books. His debut novel, A Jungle of Stars, was released in 1976, and with the huge success of Midnight at the Well of Souls two years later, he became a full-time novelist. Chalker is a passionate environmentalist who also enjoys traveling, gadgets, and computers.

He's also a well-known science fiction and fantasy lecturer who's given talks at a number of schools and universities. He is a huge fan of steamboats, particularly ferryboats, and has ridden more than 300 of them in the United States and abroad.