He was the half-brother of Inocêncio Camacho Rodrigues, the governor of the Bank of Portugal involved in the scandal caused by the thefts of Alves dos Reis.

Upon concluding his studies, he entered into the faculty of Medicine in the School of Medical-Surgery of Lisbon, completing his course in 1884, where he began his career in the parish of Torrão, Alcácer do Sal.

In 1891 he joined the Portuguese Army as surgeon-adjunct, and assigned to the military units in Tancos and later Torres Novas, a career that would ultimately make him a colonel.

By 1894 he had founded, with Ricardo Pais Gomes and Ribeiro de Sousa, the magazine O Intransigente (The Intransigent), a Republican publication that criticized the politics and propaganda of the time, which he maintained regularly until June 1895.

From 1896 to 1897 he dedicated himself to publishing and collaboration with other Republican periodicals, and developed in Évora a political action committee, realizing several conferences and commissions.

In 1902 he presented a doctoral thesis in Medicine at the University of Paris, but abandoned his practice definitively as military medic, dedicated himself completely to journalism and politics.

He promoted a conference titled A Coroa substituída pelo chapéu de côco (The Crown Substituted by the Bowler Hat), wherein he violently attacked institutional monarchism.

The publication quickly turned into an influential republican source, transforming itself into an official organ of the Partido Unionista (Unionist Party).

Brito Camacho was one of the members of the government, along with Joaquim Teófilo Braga, António José de Almeida, Afonso Costa, José Relvas, António Xavier Correia Barreto, Amaro de Azevedo Gomes and Bernardino Machado, who signed the Law of Separation specifying the separation of Church and State (on 20 April 1911).

Manuel de Brito Camacho was the author of more than thirty volumes of published works, in particular narratives and descriptions of his homeland and life in the rural Baixo Alentejo.