Objective: In cognitive behavioural therapy (CBT), case formulation (CF) is an integral process in ensuring clinicians’ work is grounded in evidence-based practice (EBP). The objective of this study was to evaluate psychologists’ perceptions and self-reported applications of CBT-CF, and whether these differed according to clinician experience, training, and professional accreditation. Method: A scale was developed to assess CF beliefs and applications by clinicians who had been practising CBT for a minimum of 6 months. The development of scale items was based on two CBT-CF conceptual models. Seventy-nine psychologists registered in Australia took part in this online survey. Results: Psychologists’ beliefs pertaining to CBT CF supported a three-factor model. On average, psychologists perceived all activities related to CF at least moderately important, and were implemented at least some of the time. However, activities related to use of external evidence were rated as less important, and less frequently implemented. Clinical psychologists endorsed theory and EBP in structuring CF as more important, which also translated into self-reported practice of CF CBT implementation relative to generalist psychologists. Conclusions: The findings indicate some gaps in the knowledge and application of CF CBT in clinical practice and has implications in strengthening clinician training in CF CBT.