Matsuoka was born as the fourth son to a shipping magnate in Kumage District, Yamaguchi Prefecture (now part of the city of Hikari).

At the age of 11, his father's business went bankrupt, and Matsuoka was sent to the United States with a cousin in 1893 under the sponsorship of Methodist missionaries to study English.

He then returned to Portland and studied law, paying his way by various odd jobs, including busboy, door-to-door salesman (of coffee) and interpreter for a Japanese contractor.

Matsuoka was also an outspoken defender of Japanese participation in the Siberian Intervention against the Bolshevik forces in the Russian Civil War.

[9] Despite his admiration of the Italian fascist movement, Matsuoka was also a supporter of the plan to settle Jewish refugees in Manchukuo.

Matsuoka was a major advocate of a Japanese alliance with Nazi Germany and Fascist Italy, whose assistance he saw as a perfect balancing force against the United States, and as such was one of the primary orchestrators of the Tripartite Pact in 1940.

On December 31, 1940, Matsuoka told a group of Jewish businessmen that he was "the man responsible for the alliance with Adolf Hitler, but nowhere have I promised that we would carry out his antisemitic policies in Japan.

[13] Ribbentrop tried to convince Matsuoka to urge the government in Tokyo to attack Singapore, claiming the British navy was too weak to retaliate due to its involvement in the Battle of the Atlantic.

However, after Nazi Germany's invasion of the Soviet Union in June 1941, Hitler proposed to Matsuoka that Japan take part in the attack as well.

Despite the military's opposition to his ideas, Matsuoka continued to loudly advocate an invasion of Russia and became increasingly reckless in his diplomatic dealings with the United States, which he believed was conspiring to provoke Japan into a war.

Following the surrender of Japan, Matsuoka was arrested by the Supreme Commander of the Allied Powers in 1945 and held at Sugamo Prison.

However, he died in prison of natural causes on June 26, 1946, before his trial on war crimes charges came up before the International Military Tribunal for the Far East.