Bernstein worked as a bank clerk and in 1872 he joined the Social Democrat Party (SDP). In the 1877 General Election in Germany the SDP won 12 seats. This worried Otto von Bismarck, and in 1878 he introduced an anti-socialist law which banned party meetings and publications.
After the passing of the anti-socialist law Bernstein emigrated to Switzerland where he became editor of the underground socialist journal, Der Sozialdemokrat. After being expelled from Switzerland he moved to England where he worked closely with Frederick Engels and members of the Fabian Society.
While living in London Bernstein gradually became convinced that the best way to obtain socialism in an industrialized country was through trade union activity and parliamentary politics. He published a series of articles where he argued that the predictions made by Karl Marx about the development of capitalism had not come true. He pointed out that the real wages of workers had risen and the polarization of classes between an oppressed proletariat and capitalist, had not materialized. Nor had capital become concentrated in fewer hands.
Bernstein's revisionist views appeared in his extremely influential book Evolutionary Socialism (1899). His analysis of modern capitalism undermined the claims that Marxism was a science and upset leading revolutionaries such as Vladimir Lenin and Leon Trotsky.
In 1901 Bernstein returned to Germany. This brought him into conflict with left-wing of the Social Democrat Party that rejected his revisionist views on how socialism could be achieved. This included those like August Bebel, Karl Kautsky, Clara Zetkin, Karl Liebknecht and Rosa Luxemburg, who still believed that a Marxist revolution was still possible.
Bernstein was elected to the Reichstag (1902-06 and 1912-18) where he led the right-wing of the Social Democrat Party. However, he sided with the left-wing over Germany's participation in the First World War and in 1915 voted against war credits.
In April 1917 left-wing members of the Social Democratic Party (SDP) formed the Independent Socialist Party. Members included Bernstein, Kurt Eisner, Karl Kautsky, Julius Leber, Rudolf Breitscheild and Rudolf Hilferding.
After the war he joining the leadership of the Social Democrat Party in condemning the German Revolution. In the government formed by Friedrich Ebert, Bernstein served as secretary of state for economy and finance.
Sidney Hook met Bernstein in 1928 and in his autobiography Out of Step: An Unquiet Life in the 20th Century (1987) recalled him talking about Eleanor Marx and Edward Aveling: "I made several efforts to arrange a meeting with Eduard Bernstein, the famous revisionist of Marx, then living in retirement. His figure and outlook, in the perspective of the fifty years after Marx's death, had grown enormously. I was put off several times, and when I finally met him, I realized why. He was suffering from advanced arteriosclerosis and was attended by a nurse. He seemed at first reluctant to talk about his reminiscences of Marx, but at the outset of our talk, to my chagrin, was eager to describe his first day at school, about which he had very vivid memories. I kept reverting to various episodes of Marx's life and to some of Marx's literary remains, which Engels had entrusted to Bernstein. His manner was benign and friendly. Only twice did he lose his composure and burst out with a stormy lucidity. The first time was when I mentioned Edward Aveling with whom Eleanor Marx, Marx's youngest daughter, had been enamored, and who had been the cause of her suicide. Bernstein rose from his chair with flushed face and agitated tone and voice and denounced him as an arch scoundrel. I did not, however, get a very coherent account of Aveling's infamy."
Eduard Bernstein died in Berlin on 18th December, 1932.