Introduction <p> Previous studies have shown a correlation between the triglyceride glucose index (TyG) and hypertension, as well as between body roundness index (BRI) and hypertension. However, there is limited research on the bidirectional mediation effects of TyG and BRI on their relationships with hypertension.</p> Aim <p> We aimed to assess the associations between the TyG with hypertension among participants with different BRI, and examine the potential mediating effect of BRI on the associations between TyG with hypertension.</p> Methods <p> This cross-sectional study involved 9,251 middle-aged and elderly individuals from the China Health and Retirement Longitudinal Study. Association between TyG and BRI, and hypertension was examined using multivariable logistic regression, restricted cubic spline analysis, and subgroup analysis. Bidirectional mediation analysis was conducted to determine the direct and indirect effects through BRI and TyG.</p> Results <p> After adjusting for potential confounders, TyG was associated with a 40% (OR: 1.40; 95% CI: 1.23–1.59) higher risk for hypertension, and BRI was associated with a 33% (OR: 1.33; 95% CI: 1.28–1.38) higher risk for hypertension. A linear association between TyG and hypertension was noted (<i>P</i>_overall&lt;0.0001, <i>P</i>_{non−linearity}=0.173), and there was a nonlinear relationship between BRI and hypertension (<i>P</i>_overall&lt;0.0001, <i>P</i>_{non−linearity}&lt;0.0001). BRI was found to mediate 11.71%, 11.66%, and 11.76% of the associations between TyG and hypertension, SBP, and DBP. No significant multiplicative and additive interactions were found between TyG and BRI on hypertension (Additive: RERI = 1.25, 95% CI: -8.03-14.17; Multiplicative: OR = 0.90, 95% CI: 0.77–1.04).</p> Conclusions <p> BRI appeared to be associated with hypertension risk and played a mediating role in the association between TyG and hypertension. Managing visceral fat and monitoring TyG levels may contribute to alleviating hypertension.</p> Graphical Abstract <p></p>