Page worked as a journalist in various parts of the United States in the 1880s and '90s and from 1898 to 1899 was editor of The Atlantic Monthly. In January 1900 he and Frank N. Doubleday founded the publishing house of Doubleday, Page and Company (afterward Doubleday and Company, Inc.) and the magazine The World's Work, which he edited until 1913. In 1911 he was one of the first to propose Woodrow Wilson (Wilson, Woodrow) as a presidential candidate. One of Wilson's first acts after his inauguration in March 1913 was to appoint Page ambassador to Great Britain.

A firm believer in Anglo-American superiority in cultural and political matters, Page at first worked amicably with both Wilson and the British government and was largely responsible for the repeal of a U.S. Panama Canal toll schedule that the British considered discriminatory. By the outbreak of war in August 1914 he had become popular with the upper class and the general public in Great Britain. Unlike Wilson, however, Page soon came to view the war as an attempt by imperial Germany to rule Europe and to substitute Prussian militaristic autocracy for the democratic ideal. Outwardly conforming to U.S. neutrality, Page expressed his disagreement with Wilson's policy of noninvolvement in private messages to the president. When the British steamship Lusitania was sunk by a German submarine (May 7, 1915), with the loss of more than 100 American lives, Page called for a U.S. declaration of war. He insisted then and later that U.S. intervention at that time would have resulted in a swift victory for the Allies. In April 1917, when Wilson did ask Congress to declare war on Germany, he used the arguments that Page had been using for two and a half years.

Always in precarious health and further weakened by his labours as ambassador, Page became so ill in August 1918 that Wilson accepted his retirement. Page died shortly after returning home.