Workplace involvement in rehabilitation for patients with musculoskeletal pain may improve work ability. Convergence Dialogue Meeting (CDM) is a model aimed at helping the patient, the care giver, and the employer to support work ability and return-to-work. Our aim was to study the effect on work ability when adding a workplace dialogue according to CDM in physiotherapy practice for patients with pain in ordinary primary care. We conducted a prospective pairwise cluster randomised controlled trial (ClinicalTrials.gov ID: NCT02609750) in primary care involving 20 primary care rehabilitation units with 1-year follow-up. Adult patients with acute/subacute neck and back pain, worked ≥4 weeks past year and not currently on sick leave or no more than 60 days of sick leave and considered at-risk of sick leave were included (n = 352). All patients received structured physiotherapy and the intervention was the addition of CDM, delivered by the treating physiotherapist. The main confirmatory outcome, work ability (defined as working at least 4 consecutive weeks at follow-up), was assessed by a weekly short text message question on number of sick leave days past week. Work ability was reached by significantly more patients in the intervention group (108/127, 85%) compared with the reference group (127/171, 74%) (P = 0.02). The intervention increased the odds of having work ability at 1-year follow-up, also after adjustment for baseline health-related quality of life (odds ratio 1.85, confidence interval 1.01-3.38). We conclude that an early workplace dialogue in addition to structured physiotherapy improved work ability significantly.