International outcry and investigative reports, notably the Casement Report, led to widespread condemnation of Leopold's regime and eventually forced him to cede control of the Congo Free State to the Belgian state in 1908.

The atrocities in the Congo Free State eventually came to light through the efforts of missionaries, journalists, and a growing international reform movement. Figures like Edmund Dene Morel, a British shipping clerk turned activist, and Roger Casement, a British consul, played pivotal roles in exposing the horrific conditions. Morel's investigations revealed the massive profits Leopold was making, contradicting the humanitarian narrative. Casement's official report, commissioned by the British government in 1903, provided damning eyewitness testimonies and detailed accounts of mutilation and systematic abuse, lending undeniable credibility to the accusations. The widespread publication of these reports and the relentless campaigning by organizations like the Congo Reform Association generated significant international pressure, particularly from Britain and the United States. Faced with overwhelming evidence and mounting diplomatic isolation, Leopold could no longer maintain his facade. In 1908, under immense pressure and with a hefty payment from the Belgian state, he was compelled to relinquish his personal control, transforming the Congo Free State into the Belgian Congo, a colonial possession directly administered by the Belgian government. While this ended Leopold's personal rule, it did not immediately resolve the deep-seated problems of colonial exploitation.