Background: Cutaneous mucormycosis is a rare but aggressive fungal infection typically associated with immunocompromised states, particularly uncontrolled diabetes mellitus. The disease can rapidly progress to systemic involvement, requiring prompt diagnosis and intervention.

Case Presentation: A 33-year-old male with no prior medical history presented with right lower limb swelling, ulcerations, and blistering. He was found to have newly diagnosed diabetes mellitus. Despite fasciotomy and broad-spectrum antibiotic therapy, the condition progressed to necrotizing fasciitis requiring a guillotine amputation. Histopathology revealed broad, aseptate, right-angled branching fungal hyphae consistent with mucormycosis. Bacterial cultures grew Proteus mirabilis and Escherichia coli. The patient deteriorated due to septic shock and multi-organ dysfunction and succumbed despite intensive care.

Investigations: Elevated renal parameters and electrolyte imbalances were noted. Histopathology confirmed cutaneous mucormycosis. Culture reports showed a polymicrobial bacterial infection.

Intervention: Right above-knee guillotine amputation, supportive care, antifungal and antibiotic therapy.

Outcome: Despite surgical and medical management, the patient died due to complications of septic shock and multi-organ failure.

Conclusion: Cutaneous mucormycosis, although rare, should be considered in patients with rapidly progressive necrotizing soft tissue infections—even in the absence of classical signs such as black eschar. This case highlights the importance of early recognition, timely histopathological examination, and prompt surgical and antifungal management to improve outcomes.