Desmoplastic fibroma is a rare primary benign bone tumour that typically affects the long bones, mandible, and pelvis. It has a similar local aggressiveness to soft tissue fibromatosis. It rarely involves the small bones of the hand. We describe an extremely rare case of desmoplastic fibroma of the proximal phalanx of the hand in a patient who presented with an aggressively enlarging but painless mass on the left ring finger. Radiological features suggested malignancy; however, an initial biopsy revealed fibrotic tissue. Trans-metacarpal amputation of the ring and little fingers and soft tissue reconstruction were performed using a local ulnar-based flap of the little finger. The final histopathological evaluation revealed desmoplastic fibroma. Aggressively growing masses in the hand should be treated according to a sarcoma management protocol, and desmoplastic fibroma should be included in the differential diagnosis.