Purpose: The development of hypertension is shown to be triggered by chronic low-grade inflammation. The dietary inflammatory index (DII) is a parameter for assessing the potential of a diet to cause inflammation. The prospective association between the DII and new-onset hypertension in Chinese adults remains unclear. Materials and methods: The nationwide cohort study included 10694 participants from 7 rounds of the China Health and Nutrition Survey. Dietary nutrient intake data were collected by 3-day 24 h dietary recalls and used to calculate the DII. The time-dependent Cox regression model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for studying the risk of new-onset hypertension, and stratified analyses were used to examine factors that may modify the association. Restricted cubic spline (RCS) regression was used to examine the non-linear relationship between the DII and new-onset hypertension. The relationship between the DII and physical activity was analyzed with the time-dependent Cox regression model. Results: The highest quartile of the DII had a significantly higher risk of new-onset hypertension compared to the lowest quartile (adjusted HR, 1.13; 95% CI, 1.02, 1.24). RCS regression results showed that the risk of new-onset hypertension increased significantly after the DII above 1.09 (P for non-linearity <0.001). The interaction results showed that the DII may play a better role (P < 0.05) in the female, age < 45 years, baseline SBP < 130 mmHg, DBP < 80 mmHg, BMI < 24 kg m-2 and moderate/heavy physical activity level subgroup. Stratified analysis results showed that the baseline SBP, DBP, obesity, and physical activity level modified the association between the DII and hypertension (P for interaction < 0.05). Conclusion: Reducing the inflammatory potential of the diet is an effective strategy to prevent hypertension in Chinese adults.