ROME—Giulio Andreotti, a seven-time prime minister who over six decades helped guide Italy out of the wreckage of World War II and into a period of economic prosperity, died Monday. He was 94.

A founding father of Italy's postwar Republic, his career stretched from the Mussolini era to the fall of the Berlin Wall. A staunch Cold War warrior and inveterate wheeler-dealer, he had deep ties to both the U.S. and the Vatican.

His...