Objective:to describe the professional competencies of nurses working in urgency and emergency services and to understand their perception of the essential competencies for professional performance and updating.Method:a sequential, mixed-methods and explanatory study, conducted with emergency nurses. To obtain the quantitative data, a questionnaire with 78 items was used, answered by 39 nurses and analyzed using descriptive statistics and non-parametric tests. In turn, the qualitative data were obtained through semi-structured interviews with 17 nurses, whose interpretation was based on inductive content thematic analysis. The data were combined by connection.Results:a high level of competence was obtained in the self-assessment of urgency and emergency nurses in Factor 2 - Relations at work and a lower level in Factor 6 - Professional excellence (p=0.036). The qualitative data corroborated positively with the “Relations at work” factor, identifying the association of knowledge and practical experience, with competencies beyond a scenario devoid of permanent education.Conclusion:despite the high levels of competence identified in emergency nurses, the strengthening of educational strategies favors professional development and recognition.