Background Distal radius fractures are very common and an increased incidence of 50% is estimated by 2030. Therefore, both operative and postsurgical treatment remains pertinent. Main aim in treating intra-articular fractures is to restore the articular surface by internal fixation and early mobilization (EM). Questions/Purposes The purpose of this study was to compare functional results between EM immediately after surgery and 5 weeks of immobilization (IM). Patients and Methods In a randomized prospective study, 30 patients with an isolated distal radius fracture were treated by open reduction and internal fixation using a single volar locking plate excluding bone graft. Fifteen patients were randomized in the EM group and 15 in the IM group. At 6 weeks, 9 weeks, 3 months, 6 months, and 1 year postsurgery, range of motion, grip strength and X-rays were evaluated. Additionally, Quick Disability of the Arm, Shoulder and Hand (QuickDASH) questionnaire, Patient-Rated Wrist Evaluation (PRWE), modified Green O'Brien (Mayo) score, and pain according to the Visual Analog Scale score were analyzed. Results Patients in the EM group had a significantly better range of motion in the sagittal plane, in grip strength up to 6 months, in the frontal plane up to 9 weeks, and in forearm rotation up to 6 weeks. Also QuickDASH and PRWE scores were better up to 6 weeks postsurgery. The Green O'Brien score differed significantly up to 1 year. At 1 year, 93% “excellent” and “good” results in the Green O'Brien score with a mean QuickDASH of 5.98 ± 10.94 and PRWE score of 4.27 ± 9.23 were observed in the EM group. No differences regarding loss of reduction, pain, duration of physiotherapy, and sick leave were noted. Conclusion EM of surgically treated distal radius fractures (without bone graft) is a safe method for postoperative aftercare and leads to an improved range of motion and grip strength at 6 months postsurgery compared with an IM of 5 weeks. Level of Evidence This is a level Ib clinical study. This study was performed at the AUVA Trauma Hospital Lorenz Böhler - European Hand Trauma Center, Vienna, Austria.