KO Magazine is a popular United States boxing magazine. It was first published in 1979, to compete with The Ring.

During the 1980s, KO Magazine, nicknamed The knockout boxing magazine, ran some popular features, such as a round-by-round section where the most important fights were described punch after punch, posters with the boxer's complete records on the back and a question and answer interview section.

During the 1990s, KO Magazine was acquired by London Publishing, becoming a sister of old rival The Ring.