Objectives Mental health workers are constantly exposed to their clients' stories of distress and trauma. While listening to these stories can be emotionally draining, professionals in this field still derive pleasure from their work. This study examined the role of personality and workplace belongingness in predicting compassion satisfaction, secondary traumatic stress, and burnout in mental health workers. Methods Mental health staff (N = 156) working in a counselling service completed a questionnaire that included measures relating to professional quality of life, the Five‐Factor Model of personality, workplace belongingness, as well as questions relating to the participants' demographic profile, work roles, and trauma history. Results The results indicated that high levels of emotional stability (low neuroticism), extraversion, agreeableness, conscientiousness, and being connected at work, are essential factors that promote the professional quality of life of mental health workers. Specifically, workplace belongingness was the strongest predictor of compassion satisfaction and low levels of burnout, while neuroticism was the strongest predictor of secondary traumatic stress. Conclusions Important implications from this study include: (a) encouraging mental health staff to increase self‐awareness of their dispositional characteristics and how their personalities affect their well‐being at work; and (b) encouraging management to facilitate practices where mental health workers feel connected, respected, and supported in their organisation.