<p>Chlorfenapyr poisoning is rare in clinical practice, with limited documented cases. This study aims to elucidate the clinical progression and pathological features of fatal chlorfenapyr poisoning through a forensic autopsy case. We present a case involving a 15-year-old male who died following oral ingestion of chlorfenapyr. Autopsy and histopathological examinations were performed, supplemented by toxicological analysis. Findings included decerebrate rigidity, cerebral edema, myocardial contraction band necrosis, pulmonary hemorrhage, and rhabdomyolysis. Histopathology confirmed neuronal damage, gliosis, and myoglobin-positive renal tubules. Toxicological analysis detected both chlorfenapyr and tralopyril in premortem and postmortem blood samples. Tralopyril levels measured 2610 ng/mL premortem and 1980 ng/mL postmortem, while chlorfenapyr levels were 320 ng/mL and 280 ng/mL, respectively. The patient exhibited delayed symptom onset, rapid deterioration, and resistance to supportive treatment. This case underscores chlorfenapyr’s systemic toxicity, particularly its impact on high-energy-demand organs. The absence of a specific antidote highlights the need for early intervention and hemodialysis. This report—the first forensic autopsy of adolescent chlorfenapyr poisoning—enhances understanding of its pathophysiology and aids clinicians in recognizing nonspecific early symptoms.</p>