After the death of his father in 1883 he changed his name to Robert Cunninghame-Graham. He returned to England and became interested in politics. He attended socialist meetings where he heard and met William Morris, George Bernard Shaw, H. M. Hyndman, Keir Hardie and John Burns. Despite his wealthy origins, Graham was converted to socialism and he began to speak at public meetings. He was an impressive orator and was especially good at dealing with hecklers.
Although a socialist, in the 1886 General Election he stood as a Liberal at North-West Lanarkshire. His election programme was extremely radical and called for the abolition of the House of Lords, universal suffrage, the nationalisation of land, mines and other industries, free school meals, disestablishment of the Church of England, Scottish Home Rule and the establishment of an eight-hour-day. Supported by liberals and socialists, Graham defeated the Tory candidate by 322 votes.
Robert Cunninghame Graham refused to accept the conventions of the House of Commons. On September 12, 1887 he was suspended from Parliament for making what was called a "disrespectful reference" to the House of Lords.
Graham's main concerns in the House of Commons was the plight of the unemployed and the preservation of civil liberties. He complained about attempts in 1886 and 1887 by the police to prevent public meetings and free speech. He attended the protest demonstration in Trafalgar Square on November 13, 1887 that was broken up by the police. During what became known as Bloody Sunday, Graham was badly beaten and arrested. Both Cunninghame Graham and John Burns were found guilty for their involvement in the demonstration and sentenced to six weeks' imprisonment.
When Graham was released from Pentonville Prison he continued his campaign to improve the rights of working people and to curb their economic exploitation. He was suspended from the House of Commons in December, 1888 for protesting about the working conditions of chain makers. Graham was a supporter of the eight hour day and made several attempts to introduce a bill on the subject. He made some progress with this in the summer of 1892 but he was unable to persuade the Conservative Government, headed by the Marquess of Salisbury, to allocate time for the bill to be fully debated.
Graham was a strong supporter of Scottish independence and in 1886 he helped establish the Scottish Home Rule Association and while in the House of Commons made several attempts to persuade fellow MPs of the desirability of a Scottish Parliament. On one occasion Graham humorously argued that he wanted a "national parliament with the pleasure of knowing that the taxes were wasted in Edinburgh instead of London".
While in the House of Commons Graham became increasingly more radical. He supported workers in their industrial disputes and was actively involved with Annie Besant and the Matchgirls Strike and the 1889 Dockers' Strike. In July 1889 he attended the Marxist Congress of the Second International in Paris with James Keir Hardie, William Morris, Eleanor Marx and Edward Aveling. The following year he made a speech in Calais that was considered by the authorities to be so revolutionary that he was arrested and expelled from France.
In the 1892 General Election Graham stood as the Scottish Parliamentary Labour Party candidate for Glasgow Camlachie. He was defeated and this brought his parliamentary career to an end. He remained active in political circles though, and helped Keir Hardie establish the Independent Labour Party.
Graham retained a strong belief in Scottish Home Rule. He played an active part in the establishment of the National Party of Scotland (NPS) in 1928 and was elected their first ever President. He was several times the Glasgow University Scottish Nationalist Association candidate for the Lord Rectorship of the University of Glasgow.
During his life Graham had a large number of books and articles published. Subject matter included history, biography, politics, travel and seventeen collections of short stories. Robert Cunninghame-Graham died on March 20, 1936.