Background Triglyceride and glucose (TyG) index and TyG‐related indices combined with obesity‐related markers are considered important markers of insulin resistance. We aimed to examine the association between the TyG index and modified TyG indices with new‐onset hypertension and their predictive ability stratified by sex. Methods and Results We analyzed data from 5414 Korean Genome and Epidemiology Study participants aged 40 to 69 years. Multiple Cox proportional hazard regression analyses were conducted to estimate the hazard ratio (HR) and 95% CI for new‐onset hypertension according to sex‐specific tertile groups after confounder adjustments. To evaluate the predictive performance of these indices for new‐onset hypertension, we calculated Harrell's C‐index (95% CI). Over a 9.5‐year follow‐up period, 1014 men and 1012 women developed new‐onset hypertension. Compared with the lowest tertile (T) group, the adjusted HR and 95% CI for new‐onset hypertension in T3 for TyG, TyG‐body mass index, TyG‐waist circumference, and TyG‐waist‐to‐height ratio were 1.16 (0.95–1.40), 1.11 (0.84–1.48), 1.77 (1.38–2.27), and 1.68 (1.33–2.13) in men and 1.37 (1.13–1.66), 1.55 (1.16–2.06), 1.43 (1.15–1.79), and 1.64 (1.30–2.07) in women, respectively. The C‐indices of TyG‐waist‐to‐height ratio for new‐onset hypertension were significantly higher than those of TyG and TyG‐body mass index in both men and women. Conclusions TyG and TyG‐body mass index were significantly associated with new‐onset hypertension only in women. TyG‐waist circumference and TyG‐waist‐to‐height ratio were significantly associated with new‐onset hypertension in both men and women. A sex‐specific approach is required when using TyG and modified TyG indices to identify individuals at risk of incident hypertension.