IntroductionOpen reduction and internal fixation with volar locking plate has become the most common fixation method in the treatment of unstable distal radius fracture (DRF). There is, however, no consensus as to whether or for how long a wrist should be immobilised after operative treatment. To date, there have been relatively few studies that have evaluated the effect of immediate postoperative mobilisation on functional outcomes. The aim of postoperative rehabilitation is to obtain a good function and to reduce impairment, recovery time, socioeconomical costs and absence from work. Therefore, there is a need for studies that evaluate the optimal method of postoperative rehabilitation to optimise wrist function and return to work.Methods and analysisThis study is a prospective, randomised, controlled trial in which a total of 240 working-age patients who undergo volar plating for DRF will be randomly assigned to either an early mobilisation group or a postoperative 2-week casting group. The aim of the study will be to compare early postoperative outcomes between the study groups. The primary outcome will be patient-rated wrist evaluation at 2 months after operation. A coprimary outcome will be the total length of sick leave. Our follow-up period will be 1 year, and secondary outcomes will include pain, patient satisfaction, perceived ability to work and complications identified at different time points. We expect those patients who undergo immediate mobilisation will have at least as rapid a return to work and function as those patients who undergo postoperative immobilisation, indicating/meaning that there will be no need for postoperative casting.Ethics and disseminationThis study will be conducted according to the Standard Protocol Items: Recommendations for Interventional Trials statement. The Ethics committee of Tampere University Hospital has approved the protocol. Ethics committee approval number is R21111, and it is accepted on 7 September 2021. The results of this study will be submitted for publication in peer-reviewed journals.Trial registration numberNCT05150925.