Abstract Background Emergency nurses play a pivotal role in delivering efficient emergency healthcare, yet they often encounter numerous challenges, especially while managing life-threatening cases, impacting both their well-being and patient satisfaction. This study seeks to identify the prevalent challenges faced by these nurses in Saudi hospitals when handling Canadian Triage and Acuity Scale (CTAS1 and CTAS2) cases, with the aim of mitigating or managing these issues in the future. Methods This study incorporated a mixed-method approach to identify obstacles in Emergency Department (ED) nursing treatment of CTAS1 and CTAS2 cases in two major Saudi Arabian hospitals. The research began with qualitative focus group interviews with expert ED nurses, followed by a quantitative survey to measure and explore relationships among the qualitative findings. Data analysis leveraged qualitative thematic analysis and principal component analysis, ensuring rigorous examination and validation of data to drive meaningful conclusions. Findings From expert interviews, key challenges for emergency nurses were identified, including resource management, communication, training compliance, and psychological factors. A survey of 172 nurses further distilled these into five major issues: patient care management, handling critical cases, administration support, patient care delay, and stress from patients’ families. Conclusion Through a mixed-method approach, this study pinpoints five pivotal challenges confronting emergency nurses in Saudi hospitals. These encompass difficulties in patient care management, the psychological toll of handling critical cases, inadequate administrative support, delays due to extended patient stays, and the stress induced by the presence of patients’ families, all of which significantly impede emergency department efficiency and compromise nurse well-being. Keywords Triage, Emergency nurses, Emergency obstacles, Emergency challenges, Saudi Arabia