Like different ethnic societies across the world, Oromo, the largest ethnic group in Ethiopia, has an indigenous institution called 'Sirna Gada' denoted hereafter as Gada System. It reported as best democratic governance institution innovated hundreds of years before the inexistence of modern democracy, more acceptable and effective up to date than formal institution within Oromo community in ruling their overall socio-economic and political courses of life. Despite the more than 83 ethnic and linguistic based groups in Ethiopia, there is a need to look for and promote the most effective and community-acceptable conflict resolution mechanism in an effort to maintain sustainable peace and security internally in the country; which could be using Indigenous informal institutions. Thus, a role of Gada institution in conflict resolution among the Gabra, Guji and Borena Oromo communities in Southern Ethiopia are one that can deserve attention in this paper. The biggest challenge of today confronting humans is not about the occurrence of conflict, but how these conflicts are fully resolved whenever they occur to prevent them from further escalating. However, this Gada institution in Gabra, Guji and Borena Oromo areas has been overlooked and received less research attention. Thus, the present paper delineates the role of Gada institution in conflict resolution among Gabra, Guji and Borena communities. The paper recommends that the indigenous values of the Gada System of Gabra, Guji and Borena Oromo are viable and needs to be recognized and encouraged. The modern efforts of promoting and protecting the Oromo indigenous Gada system cultural values of the religious, economic, social and political aspects. The political aspect of Gada system deals with the, peace building, democratic, indigenous governance values etc. Therefore, there is a need to reconsider and create space for harmonizing indigenous cultural values of this indigenous Gada institution among Gabra, Guji and Borena Oromo communities in Southern Ethiopia in line with the modern administration.