Two-dimensional (2D) materials, particularly transition metal dichalcogenides (TMDs), have gained considerable research attention in electronics and biosensing due to their exceptional electrical and physical properties. In this work, we report a molybdenum disulfide (MoS) field-effect-based biosensor for sensitive, selective, and label-free detection of cardiac troponin I (cTnI), a key biomarker for acute myocardial infarction (AMI). To enhance biorecognition efficiency, yolk-shell-structured plasmonic nanoparticles were synthesized and conjugated with anti-cTnI antibodies before being immobilized on the MoS channel surface. The resulting biosensor demonstrated high sensitivity with a limit of detection as low as 2.66 pg/mL. Selectivity tests confirmed its excellent specificity, effectively distinguishing cTnI from other interfering biomarkers. The integration of 2D MoS with yolk-shell nanomaterials provides a highly promising platform for rapid and precise AMI diagnostics.