Although cardiac arrhythmias are still a major health threat for human, there is paucity of information on the molecular mechanisms involved in this pathology. Striatin (STRN) is a multivalent protein with dynamic domains including caveolin (Cav), Calmodulin (CaM), and Protein Phosphatase 2A (PP2A) binding sites, all of which are important regulatory units of the L‐type Calcium Channels (LCC) in cardiomyocytes. Previous studies indicate that mutations/deletions of the striatin gene correlate with the development of cardiac arrhythmias in animal models. We aimed to investigate whether STRN regulates calcium homeostasis and cardiomyocyte contraction rate. Data indicate that STRN is highly expressed in atrial myocardium when compared to the ventricles. Overexpression of STRN elevated the contraction rate (~ 3 fold) and resulted in sustained levels of KCl‐induced increases in intracellular calcium in neonatal rat cardiomyocytes. Conversely, silencing (>80%) the STRN gene using shRNA was associated with decreased contraction rate (~50%) of cardiomyocytes. Interestingly, pharmacological challenge with isoproterenol (β‐adrenergic agonist) failed to improve the contraction rate of cardiomyocytes with low levels of striatin (shRNA‐STRN). Biochemical analysis (CaM pull down) revealed that the interaction between CaM/PP2A/Cav‐3/LCC was increased in shRNA‐STRN cardiomyocytes and reduced when overexpressing STRN. Collectively our data indicate that striatin is a novel regulator of cardiomyocyte calcium homeostasis and contraction rate by modulating the CaM/PP2A/Cav‐3/LCC complex and influencing the activity of the LCC in the myocardium.