After a mainly military education, he came suddenly to the throne in 1900 on the assassination of his father, King Umberto I. A tractable constitutional monarch, he accepted a Liberal cabinet and readily acquiesced in Italy's war against Turkey in 1911 and entrance into World War I in 1915.

When the strains put on the parliamentary system by the war brought Mussolini to the fore, Victor Emmanuel failed to prevent the Fascist seizure of power, though it apparently lay in his hands to do so merely by signing the decree of martial law proposed by the cabinet. He was quickly reduced to a figurehead or less by the Mussolini dictatorship, but in 1943, following disastrous Italian military reverses in World War II, capped by the Allied invasion of Sicily, Victor Emmanuel surprised the world by having Mussolini (Mussolini, Benito) arrested and installing Marshal Pietro Badoglio as premier. The move failed to extricate Italy from the war or the King from his difficult position, and finally, on June 5, 1944, the day after the Allied liberation of Rome, he named his son Crown Prince Umberto lieutenant general of the realm, relinquishing all power for himself but retaining his title of king.

In 1946 public opinion forced a plebiscite to decide between the monarchy and a republican form of government. In an effort to influence the vote in favour of the dynasty, Victor Emmanuel abdicated in favour of Umberto (May 9, 1946), but the plebiscite resulted in a victory for the republic, and both Victor Emmanuel and Umberto went into exile.