Background: Physical activity, aerobic and resistance training have established benefits to health and wellbeing, with physiotherapists playing a vital role in their promotion. Objectives: To capture UK student and graduate physiotherapists (1) knowledge of accepted guidelines and, (2) perceptions of physical activity and exercise prescription in practice. Design: National cross-sectional online survey. Methodology: A survey was conducted online among UK student and graduate physiotherapists from July to December 2021. Quantitative questions included dichotomous (yes/no), multiple-choice, and Likert scale (1-5) formats, alongside open-ended qualitative questions. Results: Of 305 respondents (18% students, 47% > 10 years' experience), 295 (97%) either "agreed" (n = 64, 21%) or "strongly agreed" (n = 231, 76%) that physical activity was a part of their role. Less than half felt the physiotherapy profession was able to provide effective physical activity (n = 149, 49%, 95% confidence intervals 43 to 54) and aerobic training (130, 43%, 37 to 48). Most knew the weekly minimum adult dosage of physical activity (257, 84%, 80 to 88) and resistance training (267, 88%, 83 to 91) but were generally unable to correctly identify aerobic and resistance training guidelines. Of those who used evidenced based guidelines regularly with patients 72% were not adopting correct guidelines for aerobic (n = 58, 72%, 61 to 80) and 46% for resistance training (n = 45, 46%, 36 to 56). Limited patient appointment duration, inadequate access to facilities and a lack of continuous professional development opportunities were perceived barriers to implementation. Conclusion: Respondents agreed physical activity and exercise are vital treatment modalities, however many lack the knowledge to deliver these interventions in line with contemporary guidelines.