Background: The development of breast cancer is influenced by variations in the antioxidant enzymes. An essential part of the body's fundamental antioxidant defense mechanism is catalase. Numerous studies indicate that the catalase gene polymorphism rs1001179 acting a critical role in the genesis of cancer. Objective: In order to determine how the rs1001179 polymorphism affects catalase (CAT) activity and the progress of breast cancer (BC) in individuals with BC, this study was designed. Methods: A spectrophotometric test was used to measure the amount of CAT enzymatic activity in serum samples. Following the extraction of genomic DNA from the blood samples, we used restriction fragment length polymorphism, polymerase chain reaction, and electrophoresis to evaluate the presence of single nucleotide polymorphism (SNP) rs1001179. Results: According to the findings, the BC group had lower CAT activity (10.605±8.490 U/ml) than the control group (16.895±8.100 U/ml). The homozygous mutants (TT) and heterozygous carriers (CT) were fewer likely to acquire BC, with odd ratios of 1.48 and 22.2, with P value 0.64 and 0.032 for the two genotypes, respectively. Between the study groups, there was a significant difference in the incidence of the T allele (P value 0.025 and OR 3.5). The wild-type CC genotype and C allele exhibited higher CAT activity than the mutant (TT and CT) and the T allele within the patient group. The results of this study propose that the CAT (rs1001179) polymorphism may contribute to the hereditary risk of BC and might be utilized as a possible tumor susceptibility marker. Conclusion: The rs1001179 SNP increased reactive oxygen species, particularly hydrogen peroxide, via decreasing CAT enzyme activity. The key factor that contributes to the development and spread of cancer is DNA damage, which can result from this buildup.