Purpose <p>To investigate the association between fish consumption and mortality risk related to cardiovascular disease (CVD) and its subtypes among Korean adults by sex.</p> Methods <p>A total of 110,134 adults were selected from the Ansan-Ansung and Health Examinees cohorts in the Korean Genome and Epidemiology Study. Fish consumption was assessed using a food frequency questionnaire and categorized into four groups: &lt; 2, 2–4, 4–7, and ≥ 7 servings/week. CVD mortality was determined from 2001 to 2021 death records provided by Statistics Korea. Cox proportional hazards regression was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality across fish consumption. Restricted cubic spline regressions were conducted to examine nonlinear dose–response relationships between weekly fish consumption and CVD mortality.</p> Results <p>Among women, higher fish consumption was associated with a lower risk of CVD mortality (≥ 7 servings/week vs. &lt; 2 servings/week: HR 0.76, 95% CI 0.54–1.07, <i>P</i> trend = 0.029). By CVD subtypes, higher fish consumption showed a significant inverse association with the risk of cerebrovascular disease mortality in women. Among men, fish consumption was not significantly associated with mortality risk related to CVD or its subtypes. A significant nonlinear inverse association with overall CVD mortality was observed in women and women with older ages and higher intake of fruits and vegetables showed a stronger association with overall CVD mortality compared to their counterparts.</p> Conclusions <p>We found that higher fish consumption is associated with a reduced risk of CVD mortality in Korean women. Sex-specific dietary strategies may be necessary for the effective prevention and management of CVD.</p>