Background and Objectives: Jehovah’s Witnesses (JW) reject the transfusion of blood components based on their religious beliefs, even if they are in danger of harm or death. In cardiac surgery, this significantly reduces the margin of safety and leads to ethical conflicts. Informed consent should be carefully documented and the patient’s family should be involved. This study aims to compare the postoperative course of JW who underwent major cardiac surgery with a similar population of non-Witnesses (NW). Patients and Methods: Demographic, procedural, and postoperative data of all consecutive JW who underwent cardiac surgery at our institution were obtained from the records. They were compared with a propensity-score-matched group of NW. Anemic JW were treated with erythropoietin and/or iron as needed. Cardiac surgery was performed by experienced surgeons using median sternotomy and cardiopulmonary bypass. Common blood-sparing techniques were routinely used. Periprocedural morbidity and mortality were statistically evaluated for both groups. Results: A total of 32 JW and 64 NW were part of the matched dataset, showing no demographic or procedural differences. EPO was used preoperatively in 34.4% and postoperatively in 15.6% of JW but not in NW. Preoperative hemoglobin levels were similar (JW, 8.09 ± 0.99 mmol/L; NW, 8.18 ± 1.06; p = 0.683). JW did not receive any transfusions except for one who revoked, while NW transfusion rates were 2.5 ± 3.1 units for red cells (p < 0.001) and 0.3 ± 0.8 for platelets (p = 0.018). Postoperative levels differed significantly for hemoglobin (JW, 6.05 ± 1.00 mmol/L; NW, 6.88 ± 0.87; p < 0.001), and hematocrit (JW, 0.29 ± 0.04; NW, 0.33 ± 0.04; p < 0.001) but not for creatinine. Early mortality was similar (JW, 6.3%; NW, 4.7%; p = 0.745). There were more pacemakers and pneumonias in JW, while all other postoperative conditions were not different. Conclusions: Real-world data indicate that Jehovah’s Witnesses can safely undergo cardiac surgery provided that patients are preconditioned and treated by experienced surgeons who use blood-saving strategies. Postoperative anemia is observed but does not translate into a worse clinical outcome. This is consistent with other studies. Finally, the results of this study suggest that all patients should benefit from optimal pretreatment and blood-sparing strategies in cardiac surgery, not just Jehovah’s Witnesses.