Chemical, biological, radiological, and nuclear (CBRN) incidents are those that involve chemical or biological warfare agents or toxic radiological or nuclear materials. These agents can cause disasters intentionally or accidentally. Hospitals play a crucial role in handling CBRN disasters. This study aimed to assess the CBRN preparedness of government hospitals in Riyadh. A descriptive cross-sectional study was conducted across government hospitals in Riyadh. All government hospitals with more than 100 inpatient beds and an emergency department met the inclusion criteria. Hospital preparedness was assessed using an adaptation of the CBRNE (chemical, biological, radiological, nuclear, or explosive event) Plan Checklist. This adaptation was chosen due to the inclusion of explosive events in hospital disaster readiness, and its structural composition of key clinical guidelines necessary for a comprehensive disaster and readiness plan. Results were described in frequencies across several domains such as foundational considerations and planning which are used to assess plan preparedness using readiness tools, training, and awareness among staff members in accordance to a pre-established emergency plan, placed procedures and their implementation, and modules for preparing for a biological incident, a chemical incident, and a radiological or nuclear incident. Of the 11 eligible hospitals, 10 participated in the study. Furthermore, CBRN considerations were included in the disaster plans of 7 hospitals. Drills had been conducted in collaboration with local agencies in only 2 hospitals. The staff had been trained to recognize the signs and symptoms of exposure to class (A) biological agents in less than half of the hospitals. Eight of the hospitals had antidotes and prophylactics to manage chemical incidents, but only half of them had radiation detection instruments. Personal protective equipment was available in all hospitals, but rapid access to stockpiles of medications was available in only half of them. Government hospitals in Riyadh demonstrated insufficient CBRN preparedness as per the CBRNE Plan Checklist. Overall, there was a lack of preemptive planning, application of pre-established policies and procedures, and adequate staff training. Furthermore, several hospitals had insufficient stockpiles of medications and in concrete plans on accessing government stockpiles in the case of an emergency. Therefore, their staffs should be trained to manage CBRN emergencies, and local drills should be conducted to improve their preparedness.