Herpes zoster involving transferred free-flap skin is rare, particularly during the immediate postoperative period. A 49-year-old man underwent release of severe post-burn contracture of the left hand and wrist and reconstruction with a lateral thoracic perforator free flap. Pruritus and erythema developed on the contralateral upper back on postoperative day (POD) 0, followed by a thoracic dermatomal vesicular eruption on POD 3 that was clinically diagnosed as herpes zoster. Intravenous acyclovir was initiated. On POD 6, morphologically similar vesicles appeared on the transferred flap, and distal partial flap necrosis subsequently demarcated. Herpes simplex virus testing was negative, but varicella-zoster virus testing was unavailable; therefore, involvement of the flap could not be virologically confirmed. This unusual temporal sequence highlights viral reactivation as a differential consideration when vesicular lesions appear during early free-flap monitoring, while standard assessment for vascular compromise must continue.