In 1890, Blatchford founded the Manchester branch of the Fabian Society, and then he launched a weekly newspaper, The Clarion in 1891. In 1893 he published some of his articles on socialism as the book, Merrie England. This influential work was largely inspired by William Morris.
He saw his work as moralist in nature, and declared his own religion of determinism, campaigning against Christianity. Suspicious of parliamentary politics, he supported the Independent Labour Party for a short while, but threw his weight behind local groups associated with his paper. These groups varied from social clubs to choirs and scout groups, and in 1900, he formed the Clarion Fellowship in an effort to unify and supplement them.
In 1902, Blatchford published a new book, Britain for the British, which aimed more at exciting the self-interest of the working class, and was intended to be more practical than Merrie England. His determinism became more clearly defined as he moved from attacking the Bible to attacking the concept of free will. In 1904, he wrote Not Guilty: A Defense of the Bottom Dog, illustrating his view that the poorest in society were in their position as a result of heredity and their environment, and had no control over their actions.
Blatchford came to concentrate on his campaign against religion at the expense of all other activity. Although still a prominent figure around The Clarion, his socialism waned. A supporter of the British government during the Boer War, in order to support the First World War, he joined the Socialist National Defence League, and then in 1924 moved to support the Conservative Party.