The need for quick and highly sensitive methods to identify cyanide remains critical due to its potent toxicity and its relevance in forensic investigations. This study presents a new forensic application of Ion Mobility Spectrometry (IMS) for the rapid detection of cyanide in postmortem blood. A streamlined sample-handling procedure was employed in which cyanide ions were converted to hydrogen cyanide (HCN), released into the headspace, and introduced directly into the IMS system. The analytical approach provided a linear response between 50 and 2000 μg L⁻¹ (R² > 0.99), with strong sensitivity reflected by a limit of detection of 20.4 μg L⁻¹ and a limit of quantification of 68.1 μg L⁻¹. Precision was satisfactory, with intra- and inter-assay variation below 15%, and extraction recoveries ranged from 82% to 94%. Following full validation, the method was successfully used to evaluate postmortem blood specimens from forensic casework, allowing for rapid and reliable cyanide quantification in every analyzed sample.