Methanol poisonings caused by drinking industrial alcohol remain a severe problem worldwide. Education on types of alcohol and their harmfulness and legal regulations limiting the industrial alcohol trade seem to be the keys to reducing the number of poisonings. Methanol distribution in different tissues after absorption is not well understood. This research aimed to quantify the methanol and formic acid distribution in body fluids and tissue material in post-mortem samples collected from 19 fatal victims of massive intoxication with industrial alcohol in the Silesia Region (Poland) who died between April and June 2022. The samples were analyzed using a gas chromatography–flame ionization detector (GC-FID), and correlation coefficients for methanol and formic acid were determined. The results show a wide distribution of methanol and formic acid in human post-mortem biological fluids (blood, urine, vitreous humor, bile, and cerebrospinal fluid) and tissues (muscle, kidney, liver, spleen, lung, and brain). The strongest correlation for methanol concentration in blood and body fluids/tissues was obtained in the cerebrospinal fluid (r = 0.997) and for formic acid in muscle tissue (r = 0.931). The obtained results may be a valuable tool in toxicological analysis and improve medical standards of early diagnosis and targeted treatment.