Born in New Mexico in 1921, in his early teens Mauldin decided that he wanted to become a professional cartoonist and after high school he attended the Academy of Fine Art in Chicago. Joining the United States Army in 1940, he began producing cartoons for the 45th Division News.
In 1943 he took part in the invasions of Sicily and Italy, and the following year he became a full-time cartoonist for the Stars and Stripes. His cartoons often featured two infantrymen called Willie and Joe who are still predominant in his later works. After Ernie Pyle, America's most popular journalist in the Second World War, wrote an article about his work he was picked up by United Feature Syndicate in 1944 and his cartoons began appearing in newspapers all over the United States. His cartoons often reflected his anti-authoritarian views and this got him in trouble with some of the senior officers, including General George Patton, who wrote a letter to the Stars and Stripes and threatened to ban the newspaper from his Third Army if it did not stop carrying "Mauldin's scurrilous attempts to undermine military discipline." General Dwight D. Eisenhower did not agree, fearing that any attempt at censorship would undermine army morale, therefore he arranged a meeting between Mauldin and Patton in March 1945 where Mauldin had to endure a long lecture on the dangers of producing "anti-officer cartoons" in which he responded by arguing that the soldiers had legitimate grievances that needed to be addressed.
In 1945, Mauldin's cartoons on the Second World War won the Pulitzer Prize, and being the youngest person to be awarded the prize, he was now one of the best-known cartoonists in the United States. His book, Bill Mauldin's Army, was published in 1951. As a member of the ‘United Feature Syndicate’, Mauldin's cartoons attacking racism, the Ku Klux Klan and McCarthyism appeared in newspapers all over the United States. Mauldin's cartoons were unpopular with the newspapers in small towns and he had difficulty getting them published. In 1959 he won another Pulitzer Prize for his cartoon, “I won the Nobel Prize for Literature. What was your crime?” Bill Mauldin died of respiratory failure at a nursing home in Newport Beach, California, on 22nd January, 2003.