Introduction Various polymorphisms in the beta-2 adrenergic receptor (ADRB2) gene have been associated with cardiometabolic risk factors, such as hypertension, dyslipidemia, type 2 diabetes mellitus and obesity contributing to the physiopathology of these chronic conditions. However, the association of the single nucleotide polymorphism (SNP) rs12654778 at the ADRB2 gene with metabolic changes has been poorly studied and there is no information on the Chilean adult population. Objective To investigate the association between the rs12654778 SNP at the ADRB2 gene with cardiometabolic risk markers in a Chilean adult population. Methods We conducted a cross-sectional study including 404 participants from the GENADIO study whom were genotyped for rs12654778 and categorized into GG, AG, and AA genotypes. Associations with cardiometabolic risk markers, such as blood pressure, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, blood glucose and insulin were examined using multivariate regression analysis, while statistical models were adjusted for sociodemographic and lifestyle variables. Results Our findings indicate a significant association between the presence of the protective genotype (AA) of the rs12654778 polymorphism and lower low-density lipoprotein cholesterol levels corresponding to 8.75 mg/dL per each copy of the protective allele (maximally adjusted model). No significant associations were seen for the remaining variables. Conclusion The AA genotype of the rs12654778 SNP at the ADRB2 gene had a protective effect specifically against low-density lipoprotein cholesterol levels. This is the first study ever conducted in Chile on this SNP of ADRB2 and one of the few conducted worldwide to establish an association between the rs12654778 SNP at the ADRB2 gene and LDL cholesterol.