House's greatest influence came during the presidency of Woodrow Wilson, whom he helped elect in 1912. Serving as Wilson's closest confidential advisor, he shaped domestic appointments and acted as the president's personal envoy to European capitals during World War I. He contributed to the drafting of the Fourteen Points and represented the United States at the Paris Peace Conference of 1919, though disagreements over the Versailles Treaty later strained his relationship with Wilson.
As a writer, House is best remembered for his anonymously published political novel "Philip Dru: Administrator" (1912), which outlined his progressive vision of American governance. His private correspondence and reflections were later compiled in the four-volume "The Intimate Papers of Colonel House" (1926–1928), an invaluable resource for historians studying the Wilson era and the diplomacy of World War I.