Objective <p>There is a paucity of data regarding the association between malnutrition and mortality in China. This study aimed to explore the association between the geriatric nutritional risk index (GNRI) and all-cause and cardiovascular mortality in Chinese adults with hypertension.</p> Methods <p>A total of 14,221 participants with hypertension (mean age, 63.8 ± 9.4 years; 47.2% males) were included in a prospective cohort analysis. GNRI was calculated using the following formula: [1.489 × serum albumin (g/L)]﹢[41.7 × (actual weight/ideal weight)]. The primary outcomes of this study were all-cause and cardiovascular mortalities. Cox regression analysis, restricted cubic spline analysis, and Kaplan–Meier curves were used to evaluate the association between GNRI and mortality.</p> Results <p>Over a mean follow-up of 3.9 years, 805 deaths were recorded, of which 397 were due to cardiovascular disease. Overall, GNRI was significantly negatively associated with all-cause and cardiovascular mortality. Compared with participants with normal nutritional status, the hazard ratios for all-cause and cardiovascular mortality were 1.78 (95% CI: 1.41–2.24) and 1.66 (95% CI: 1.17–2.33) among those with mild malnutrition, and 2.13 (95% CI: 1.46–3.11) and 2.38 (95% CI: 1.41–4.02) among those with moderate-to-severe malnutrition, respectively. The association between GNRI and all-cause (<i>P</i> for interaction = 0.004) and cardiovascular mortality (P for interaction = 0.002) was stronger in non-overweight individuals (body mass index (BMI) &lt; 24 kg/m2) than in those who were overweight (BMI ≥ 24 kg/m2).</p> Conclusion <p>Malnutrition independently increases the risk of all-cause and cardiovascular mortality in individuals with hypertension.</p>