Several cases of myocarditis and pericarditis have been reported after mRNA COVID-19 vaccination. Interestingly, most cases were seen in male adolescents and young adults, commonly after 3-4 days of the second dose of mRNA vaccine. The vaccine contains the viral spike glycoprotein in the nucleoside-modified mRNA of the coronavirus that activates the proinflammatory cascades and immunological pathways, which can cause myocarditis and pericarditis. Here we report a case of a middle-aged Caucasian male who presented with progressive dyspnea, fever, and chills seven days after the second dose of the COVID-19 vaccine. He was found to have pericarditis with massive hemorrhagic pericardial effusion, large bilateral pleural effusions, circulatory shock, and cardiac arrhythmia. The patient required pericardiocentesis and thoracentesis and was discharged home on antiarrhythmic and anti-inflammatory therapy. Our case report describes a correlation between mRNA COVID-19 vaccine and pericarditis, suggesting the importance of pharmacovigilance and reporting of adverse outcomes and encourages a high index of clinical suspicion in physicians to facilitate early diagnosis and interventions.