Background Free vascularized fibular graft is useful in upper extremity long-bone reconstruction. The authors studied the reliability and long-term outcomes of this technique. Methods The authors included 20 patients with a minimum follow-up of 24 months in this study, and retrospectively reviewed patients' hospital records and used a preinformation form, the Disabilities of the Arm, Shoulder and Hand (DASH), the Lower Extremity Functional Scale (LEFS), and the 15D health-related quality of life (HRQoL) instrument to perform a cross-sectional assessment. Results A total of 9 adults and 11 children underwent vascularized fibular transfer for radical tumor resection (n = 13), infection (n = 1), injury (n = 3), or secondary pseudoarthrosis (n = 3) in various locations of the upper extremity. The median follow-up period was 6 years. Six reoperations proved necessary: one early reanastomosis and five revisions with cancellous bone grafting to enhance union. Altogether, 19 of the 20 grafts survived: one graft failed due to infection. One arm was amputated due to tumor recurrence. The median duration of bone union was 12 months. One graft never achieved distal union, whereas another developed nonunion after a stress fracture. Ten patients completed the questionnaires, with a median of 15.3 years postoperatively. The results revealed functional capabilities ranging from no restrictions to significantly impaired, and an HRQoL comparable to that of an age-standardized general population. Conclusion The free vascularized fibular graft is viable in different age groups to reconstruct upper extremity long-bone defects in cases of radical bone resection, extensive injury, and diaphyseal pseudoarthrosis. The long-term outcomes support the use of this technique.