Nutrition and genetics have individual roles in systemic arterial hypertension (SAH); however, they can interact, influencing the regulation of blood pressure (BP) levels. The aim of this study was to evaluate the available evidence regarding gene–nutrient interactions in modulating BP levels in adults with SAH. The review followed the recommendations of the Joanna Briggs Institute and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. Twelve studies met the inclusion criteria for this review, reporting on 20 genes and 31 single nucleotide polymorphisms (SNPs), with 19 of them associated with BP variations. The most frequently evaluated SNPs were ACE rs4646994 and AT1R rs5186. Among the nutritional interventions, dietary sodium content was the focus of most studies (n = 11). Interactions with sodium consumption were observed for the following SNPs: KDM1A rs587168, EDNRB rs5351, LSS rs2254524, IRS1 rs1801278, KCNK9 rs6997709, ACE rs4646994, GNB3 rs5443, PPARG rs4684847, EDN1 rs5370, BCAT1 rs7961152, IL18 rs5744292, NOS3 rs2070744, and AT1R rs5186. In the presence of a diet rich in fruits and vegetables, moderate alcohol consumption, and reduced sodium intake, the SNP AT2R rs11091046 was associated with a decrease in BP levels. Furthermore, the SNP MTHFR rs1801133 exhibited an interaction with riboflavin supplementation in affecting BP levels. The evidence regarding the interaction between genetics and diet on BP levels remains limited. Among the existing findings, an interaction was observed between sodium, calcium, riboflavin, and specific polymorphisms; however, the underlying mechanisms for these interactions have yet to be identified. Note: This paper is part of the Nutrition Reviews Special Collection on Precision Nutrition.