PURPOSE Proximal four-quarter amputation poses a significant functional and reconstructive challenge for oncological and plastic surgeons. Chronic pain from nerve stump and phantom limb phenomena, remains a considerable burden for patients with variable treatments and outcomes. METHODOLOGY This case report is of a 70-year-old female with locally advanced myxofibrous sarcoma of the right axilla, measuring 10cm x 15cm, abutting the subclavian artery, vein and mid-third of the clavicle. Extensive soft tissue involvement of the pre-pectoral posterior thorax and upper arm skin precluded localised skin flap closure for the four-quarter amputation. RESULTS An innovative approach utilizing a free fillet flap to cover the residual defect was successfully used. Following tumour excision, a mid-humeral amputation was performed. The forearm was circumferentially degloved and raised on the radial and ulnar arteries, alongside the deep venous commitantes and superficial cephalic and basilic veins. Proximal dissection of the median, ulnar, and radial nerves down to the distal arm, in conjunction with the brachial artery and vein, facilitated the surgical anastomosis of the free flap end to end with the subclavian vessel stumps on the proximal side of oncological excision. Nerve stumps were coapted to the open cords of the brachial plexus for effective pain management. The patient experienced an uncomplicated post-operative recovery and discharged two weeks post-procedure without analgesia. CONCLUSION The free fillet flap represents a highly innovative strategy for managing complex, locally advanced tumours of the axilla and mitigates potential donor site morbidity associated with larger free flap reconstructions.