A strong believer in international unionism, Gompers helped to organize the Pan American Federation of Labor, an international forum for Latin American trade unionists. He also actively supported the International Federation of Trade Unions,which sought to establish uniform labor laws and to prevent the movement of strikebreakers from country to country.

But when World War I erupted in Europe, his faith in internationalism was tested. An avowed pacifist until it seemed clear that the United States would enter the war, Gompers accepted an appointment to the Advisory Commission of the Council of National Defense, the federal agency established to organize the nation’s preparedness program. As chairman of the CND's Committee on Labor Gompers helped to mobilize the wartime workforce, to shore up labor’s support – both at home and abroad – for the war effort, and to enact government labor policies to increase production, reduce industrial conflict, and advance labor’s wage and hour standards.

Nationally recognized as a labor statesmen by the time the war ended late in 1918, Gompers represented the United States on the International Labor Legislation Commission that met in Paris, in 1919, as part of the peace conference. He not only helped to draft a charter of basic labor rights that included the right to organize, to work an eight-hour day and a six-day week, and to earn living wages and equal pay for equal work, but he also helped to establish the International Labor Organization, a permanent board designed to bring together representatives of governments, employers, and workers to promote and protect those rights.

Samuel Gompers dedicated his life to working for a new order of things: a revolution based on the evolution of trade unionism, the progressive improvement of working and living conditions, and the emergence of the working class as an equal partner in industrial life. When he died on December 13, 1924, in San Antonio, Texas, his farewell message (which he gave to a colleague two days before his death) summed up his life's work: "Say to them that as I kept the faith I expect they will keep the faith. . . . Say to them that a union man carrying a card is not a good citizen unless he upholds the institutions of our great country, and a poor citizen . . . if he upholds the institutions of our country and forgets the obligations of his trade association."