Introduction: Burnout from chronic occupational stress poses a psychosocial risk among mental healthcare professionals exposed to emotional demands (World Health Organization, 2019; Nagle et al., 2024), compromising well-being, care quality and organisational functioning (O’Connor et al., 2018; Bykov et al., 2022). This study assessed knowledge, burnout and psychological well-being among mental healthcare professionals in Portugal and analysed associations and group differences. Methods: A descriptive–correlational cross-sectional study was conducted with 199 professionals using an anonymous online survey in October 2025. The instrument included sociodemographic variables, burnout-related knowledge, the Copenhagen Burnout Inventory and the reduced General Psychological Well-Being Questionnaire (both validated for Portugal). Analyses comprised descriptive measures, normality assessment, parametric/non-parametric tests and internal reliability (α≥0.86). This study was approved by the Ethics Committee (ref. no. 2025-109). Results: Of the 199 participants, 75.4% were female and 50.8% held a bachelor’s or master’s degree (38.2%), with nurses predominating (78.9%). Most worked rotating shifts (60.8%), and 45.7% had been advised to seek psychological support. Participants demonstrated strong burnout knowledge, with only 9% believing that work–life boundaries are irrelevant. Burnout was moderate (M≈46/100) and well-being likewise (M≈3.1/5), with a strong negative correlation (r=−0.80). Older and more experienced professionals showed lower burnout. Burnout was higher in rotating-shift workers (p=0.048) and those advised to seek support (M=49.3 vs 43.1; p=0.003), who also showed lower well-being (p<0.001). Conclusions: Findings indicate a psychological burden among mental health professionals, especially those in rotating shifts and reporting support needs. The inverse burnout–well-being association reinforces the need for organisational strategies that foster healthier work conditions. Limitations include the cross-sectional, self-report design. Future studies should adopt longitudinal approaches and evaluate targeted interventions to mitigate burnout.