Background Promoting physical activity is an important part of patient care in primary care and has been investigated in many studies with a wide range of intervention characteristics, often including external support. It is unclear, however, if promoting physical activity is effective. Aim To investigate the effectiveness of behaviour change interventions to promote physical activity in primary care. Design and setting This is a systematic review and meta-analysis to evaluate physical activity promotion in a primary care setting. Method EMBASE, MEDLINE, PsycInfo, and the Joanna Briggs Institute Database were searched for ‘physical activity’, ‘interview’, ‘motivation’, ‘primary care’, and equivalent words to identify randomised controlled trials with physical activity as the outcome at patient level. Results The review identified 25 eligible studies. The quality appraisal showed that most studies reported insufficient details regarding randomisation, group allocation, blinding, and fidelity of intervention delivery. The included studies reported a wide range of interventions with varying numbers of follow-up visits or phone calls. The overall effect size for interventions with a 6-month follow-up interval was 0.04 (95% confidence interval [CI] = −0.06 to 0.14), and for interventions with a 12-month follow-up interval it was 0.19 (95% CI = 0.03 to 0.36). Only one intervention based on three motivational interviewing sessions achieved a moderate effect. Conclusion Counselling to promote physical activity in primary care has a limited effect on patients’ behaviour and it might not, on its own, be enough to change physical activity behaviour.