Harold Arundel Moody was born in 1882 in Kingston Jamaica to Charles Ernest Moody and his wife Christina Emmeline Ellis. From early on he was a devout Christian and was active in the Congregational Union, Colonial Missionary Society (chairman) and later the Christian Endeavour Union (1936).

In 1904, he moved to England to study medicine at King's College but was refused work because of his skin colour. He eventually set up his own practice in 1913 and slowly started to make a living. In the same year, he married Olive Mable Tranter, a white nurse. They had six children. In 1923, Moody spoke at the opening of the Indian Students' Hostel in Gower Street and lectured there again in early March 1930.

On 13 March 1931, he formed the League of Coloured Peoples (LCP) at a meeting at the YMCA, Tottenham Court Road, London, with the help of Charles Wesley, an African-American history professor visiting Britain. Other original members included Belfield Clark, George Roberts, Samson Morris, Robert Adams and Desmond Buckle. More prominent members included C. L. R. James, Jomo Kenyatta and Una Marson. The objects of the LCP was 1) to promote and protect the social, educational, economic and political interests of its members; 2) to interest members in the welfare of coloured peoples in all parts of the world; 3) to improve relations between the races and 4) to co-operate and affiliate with organizations sympathetic to coloured people. In an address delivered by Moody at Friends House on 18 October 1932, he emphasized that: 'For the practical purpose of the League [...] our work is mainly confined to people of African descent - at present mainly West Indian and West African - although we have some Indians in our ranks.' (Moody, 'Communications' (1933), p. 94) The LCP focused more on African rather than South Asian issues. However, in 1935, R. S. Nehra, who had come to Britain via East Africa served on the executive of the LCP, and the League hosted events for South Asians, for example for Gandhi when he visited London.

In 1933, Moody also became involved in the Coloured Men's Institute. The CMI was set up by Kamal Chunchie in 1926 as a religious, social and welfare centre for sailors. In 1930, the Institute folded but was re-established by Chunchie again in 1933. This time Moody was involved along with Shoran Singha, a Christian Sikh and YMCA worker, Canon H. L. R. Sheppard, R. K. Sorabji and Lady Lydia Anderson among them.

Pastor Kamal Chunchie was Vice-President from 1935 to 1937. In the early years, the LCP was largely a social club but as the 1930 progressed the organization campaigned on political issues such as the working-class struggles in the Caribbean, the campaign to restore British citizenship to 'coloured' seamen in Cardiff in 1936, and against the colour bar in Britain. The LCP gained influence during the Second World War and lobbied for the rights of black servicemen and women in the armed forces. In 1944, the LCP organized a conference in London and a 'Charter for Coloured Peoples' was drawn up. Many of the elements of that charter foreshadowed the resolutions of the Pan-African Congress held in Manchester the next year, though Moody did not attend that conference. Moody remained the president of the LCP until his death. In the winter of 1946, Moody went on a tour of the West Indies in order to raise money for a cultural centre in London. He fell ill and died shortly after his return to London in April 1947. The LCP continued for a few more years but closed in the early 1950s.