Literature on practitioner psychologist supervision remains underdeveloped. This mixed-methods, descriptive and exploratory study provides information about the supervisory practices of 72 registered practitioner psychologists in the UK. The primary purpose of this study was to characterise the supervision that practicing clinical and counselling psychologists receive. In addition to addressing the frequency; process and practices of supervision within this population, the study looked at the between-specialty differences in the use of supervision and the impact that practitioners' self-ratings of clinical mastery had on supervision. Participants completed an online survey. The quantitative findings showed that supervision was held at regular intervals; had an individual rather than group supervision format; and relied heavily on self-reporting. The participants reported engaging in supervision almost three times per month and were in supervisory relationships spanning multiple years. Supervisors were often line managers assigned to the role, which raises multiple relationship issues. The qualitative data, thematically analysed, produced three themes which highlighted the benefits of (a) having a space for personal development, reflection and mentoring; (b) the direction and instruction that supervision had provided them; and (c) how they valued the relational elements of the supervision experience. The findings presents valuable descriptive information about the supervision experiences of practitioner psychologists, how supervisors are assigned, how much supervision experienced psychologists undertake, and the benefits these supervisees report deriving from supervision. Practitioner psychologists may reflect on how they receive/provide supervision and how they could tailor supervision to the needs of their supervisees and to their own competencies.