The Brahmo Samaj was a monotheistic sect of Hinduism. The movement began through meetings of Bengalis in Calcutta in 1828. One of the leading figures was Ram Mohun Roy. This group was known as the Brahmo Sabha. In 1831, Roy visited England as a reforming ambassador and died there in 1833. He was buried in Bristol and his funeral sermon was conducted by Lant Carpenter, a Unitarian minister.

Debendranath Tagore, the father of Rabindranath Tagore, was a key member of the Brahmo Sabha. In 1843 he was involved in the creation of the Brahmo Samaj. Keshub Chunder Sen, a disciple of Tagore, joined the Samaj in 1857 but broke away in a formal schism in 1866. This schism was called the Brahmo Samaj of India. In 1870, Sen visited Britain and met with Mary Carpenter, the daughter of Lant Carpenter. Together they founded the National Indian Association, an organization designed to promote social reform in India and provide a meeting place for Indians and British people in Britain. Sen returned to India and created a major schism in the reforming society of the Brahmo Samaj when he married his 14-year-old daughter to the Maharaja of Cooch Behar, violating the Brahmo Marriage Act.

However, the Brahmo Samaj (in its various guises) continued to flourish in India and particularly Bengal. Rabindranath Tagore's Visva Bharati University was founded in 1921 as an expression of Brahmo universalism. The influence of Ram Mohun Roy and Keshub Chunder Sen in Britain could also be seen into the twentieth century. The cemetery where Roy was buried became a pilgrimage spot for Brahmos visiting the UK and the National Indian Association convened annual remembrances on the anniversary of Sen's death.