When disaster strikes resulting in mass casualties, the number of victims rapidly exceeds locally available intervention resources thereby necessitating exceptional response arrangements. When these tragic and traumatizing large-scale events occur, the public expects the local disaster response entities to be on hand to provide much needed assistance. Whereas the ultimate goal of any emergency medical response is to obtain the best possible intervention for the greatest number of casualties, research indicates that the efficacy of the emergency medical services (EMS) organization's response to past major incidents in Nairobi County, Kenya, has been inefficient. The aim of this study was to address this gap by examining the organizational attributes of EMS organizations that influence reliable disaster response to Mass Casualty Incidents (MCIs) in Nairobi County Kenya. The specific objective of the study was to examine EMS personnel's perceptions of organizational strategies that support reliable disaster response during MCIs in Nairobi County, Kenya. The study was guided by the high reliability theory as an approach for enhancing reliable emergency medical response performance in dynamic high-risk settings such as mass casualty disaster events. Non-probability convenience sampling approach was used to draw a target study population of 71, out of which a sample size of 54 study respondents comprising certified emergency medical technicians in fulltime employment by EMS agencies in Nairobi County was used. The study used the sequential explanatory quantitative method design. The data for the study was obtained through questionnaires and document analysis. Data were analyzed using descriptive statistics: frequency tables and diagrams were used to present quantitative data. The questionnaire measure of internal consistency yielded a reliability of Cronbach alpha α = .82. The study findings reveal that the EMS personnel in Nairobi County perceive that the EMS agencies' organizational strategies manifest HRO-like attributes to support reliable disaster response during MCIs. The study findings provide a mindfulness theoretical approach that EMS organizations can adapt to maintain reliable disaster response performance when dealing with the unexpected especially during response to MCIs. The study recommends that to support reliable disaster response performance especially during MCIs, EMS agencies should consider harnessing the existing organizational strategies using mindfulness strategies supported by disaster response policies in Nairobi County, Kenya.