Objective: In patients undergoing heart surgery, severe pain is common and may raise the risk of heart conditions, morbidity, and death. The study's goals were to evaluate post-cardiac surgery pain predictors, such as clinical variables and depression, as well as perioperative Pain Severity (PS). Methods: The research included 98 heart surgery patients in total. PS was analysed utilizing a Numerical Rating System (NRS). From the second day after surgery through the seventh day, pain levels were monitored daily. Clinical data was obtained, and depression levels were determined utilizing the Center for Epidemiological Study of Depression (CES-D). Results: From pre-operative levels, pain severe dramatically increased while hospitalized, peaking at day 2 after surgery. Higher CES-D preoperative values in gender, heart function, smoking, and a high Body mass index (BMI). Preoperative CES-D ratings were considerably higher for patients in severe pain than for those with no pain or mild pain. Patients experiencing severe pain (NRS 7 to 10) exhibited considerably greater white blood cell (WBC) counts than those free of pain or mild pain (NRS 0 to 6) (p=0.01). However, there was no association between maximum WBC levels after surgery and CES-D scores. Conclusion: Following surgery, PS considerably increased and was linked to depressive symptoms, gender, heart function, BMI, and smoking. These variables could be used as a starting point for detection and treatment to help stop the progression of acute pain into chronic pain.