Introduction: It can be challenging to treat proximal humeral non-union (PHN). The challenge gets compounded when they are presented either late or after previous surgery. The challenges are far greater due to small proximal fragments, scalloping of the head, medial bone defect, osteoporosis, soft tissue contractures, and problems related to the previous implants. Materials and Methods:In this retro-prospective study (2007–2020), we report on six cases of PHN which were presented to us more than 5 years after the original injury and managed using an intra-medullary autologous fibular strut graft (FSG) along with fixation with a proximal humeral locking plate and cancellous bone grafting. We quantified shoulder function based on constant score and disabilities of the arm, shoulder and hand (DASH) score. Results: The mean age of patients is found to be 54.3 years (range, 22–74 years) with females dominating our study. The mean pre-operative constant score is 26.33 which improved to 71.83 in the post-operative period. The mean DASH score is 77.98 preoperatively, which improved to 19.5 postoperatively. The paired sample t-test compared the difference in mean of the pre-operative and post-operative scores, which shows significant improvement in outcome. Conclusion: Even in very late PHN in poor-quality bone, the additional use of intramedullary strut grafts provides structural support to the fixation and further enhances the ability to withstand the load-start early motion and have a satisfactory functional outcome. Keywords: Non-union, proximal humerus non-union, proximal humerus fracture, proximal humerus internal locking system, locking plate, autogenous fibular strut graft.