Background <p>Congestive heart failure (CHF) is a critical condition resulting from impaired blood pumping, leading to fluid accumulation. While calcium plays a vital role in skeletal health and muscle contraction, its potential in preventing CHF remains unclear.</p> Objectives <p>This study aimed to investigate the relationship between calcium intake and the risk of CHF using data from the National Health and Nutrition Examination Survey (NHANES) collected between 2003 and 2018.</p> Methods <p>After completing the questionnaire, participants were classified into CHF and control groups, with calcium intake considered as the primary exposure variable, alongside categorical factors such as age and race. Statistical analyses included t-tests and chi-square tests. A subsequent risk stratification analysis assessed the impact of various covariates on CHF. Additionally, Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to identify optimal predictor variables, and model performance was evaluated using the receiver operating characteristic curve.</p> Results <p>A total of 3,083 participants were included in the study. Baseline characteristics revealed significant differences in race (<i>p</i> = 0.004), education (<i>p</i> = 0.019), fasting glucose (<i>p</i> = 0.047), and calcium intake (<i>p</i> = 0.020) between the CHF and control groups. In model 3, calcium intake was significantly associated with a reduced risk of CHF (<i>p</i> &lt; 0.001, OR = 6.37 × 10^–4, 95% CI = 1.47 × 10^–4 − 1.13 × 10^–3), acting as a protective factor (OR &lt; 1, 95% CI = 1 × 10^–6 − 1 × 10^–5). LASSO regression further identified calcium intake as a predictor variable.</p> Conclusion <p>Calcium intake serves as a protective factor against CHF, potentially lowering its risk. These findings provide theoretical support for the prevention and diagnosis of CHF.</p>