Objective: To identify factors related to the frequency of physical activity (PA) promotion by health professionals working in cardiac and/or pulmonary rehabilitation. Methods: A cross-sectional online survey of health professionals working in cardiac and/or pulmonary rehabilitation in Australia was conducted between July and November 2022. Results: A total of 71 health professionals from four disciplines (physiotherapy, nursing, exercise physiology, occupational therapy) completed the survey. The majority agreed that PA promotion was part of their role. Despite this, only half of the participants encouraged ≥ 10 patients per month to be more physically active. In logistic regression modelling, health professionals that measured patients’ PA levels (odds ratio 8.04, 95% confidence level 1.45–44.19) and prioritised PA promotion regardless of other patient problems (odds ratio 3.3, 95% confidence level 0.74–14.82) were much more likely to frequently promote PA to patients. Conclusion: Measurement of patients’ PA levels within cardiac and pulmonary rehabilitation and making PA promotion a priority may impact the implementation of PA promotion within these programs. Practical Implications: Physical activity measurement as a key performance indicator in cardiac and pulmonary rehabilitation is indicated. This may be an important strategy to increase physical activity promotion by cardiac and pulmonary rehabilitation health professionals.