The muscarinic acetylcholine receptor M3 (M3-mAChR) is involved in various physiological and pathological processes. Owing to specific cardioprotective effects, M3-mAChR is an ideal diagnostic and therapeutic biomarker for cardiovascular diseases (CVDs). Growing evidence has linked M3-mAChR to the development of multiple CVDs. This review summarizes the expression patterns, functions, and underlying mechanisms of action of M3-mAChR in CVDs, especially ischemia/reperfusion injury, cardiac hypertrophy, and heart failure.