In 1974, in France , during a worldwide campaign for Amnesty International, an Italian Pastor, Tullio Vinay, testifies of repeated cases of torture in South Vietnam . Extremely moved and upset by his testimony, two French protestant women, Hélène Engel and Édith du Tertre decide to set up an ecumenical group to increase awareness among Christians about the atrocity of torture. As a result, on June 16th, 1974, forty Protestants, Catholics and Orthodox Christians start Action by Christians for the Abolition of Torture (ACAT).

ACAT-Canada is initiated in 1984, by Father Gabriel Villemure and Mrs Denise Bonfils, in St-Leon-of-Westmount parish in Montréal.

In 1987, the International Federation of ACAT (FIACAT) is created. It brings together ACAT National Associations from four continents. This new structure now allows ACAT to participate in world-wide organizations such as the UN, where it has been granted consultative status and a permanent seat. Today, ACAT is active in thirty countries.

In 2010, Stephen Scharper, a University of Toronto religious studies professor, and Simon Appolloni, a PhD student launched an English chapter of ACAT Canada.