This study was designed with the aim of assessing the effectiveness of decentralization of disaster risk management in Borana zone and South-West Shawa zone of Oromia region. A mixed research approach was used to collect data from federal, regional, zonal, district (woreda), and ward (kebele) representatives. Focus group discussions and key informant interviews were the qualitative methods used to collect data, while survey questionnaires were distributed to experts to collect quantitative data. The qualitative data were analyzed using content analysis whereas the quantitative data were analyzed using STATA software version 14. The findings of the research have shown that, the actors are aware of Busa Gonofa as a new indigenous self-help institution. The policy on decentralization of disaster risk reduction was better understood at the federal, regional, and zonal levels of the government tiers than at the woreda and kebele levels. Administrative decentralization was found to be more effective than fiscal and political decentralization. The decentralization of Ethiopian disaster risk reduction is incomplete with limited effectiveness. There exists significant difference between Borana and South-West Shawa zones in decentralization of disaster risk management. The implementation of decentralization was constrained by training, technology, collaboration, financial resources, skill and knowledge, institutional arrangement, and local capacity. Hence, there is a need to address these challenges and make continuous efforts to focus on local-level capacity building in terms of empowerment of actors through training, technology, and financial resources for adaptation and mitigation to drought in Borana and flood in South-West Shawa zones respectively.