Background <p>Nutritional status, recognized as a modifiable determinant of oral health, has recently gained increasing attention in the context of edentulism. The triglyceride–total cholesterol–body weight index (TCBI) is a novel nutritional indicator derived from routine clinical measures. However, its association with edentulism remains unclear. This study was designed to assess the association between TCBI and edentulism risk.</p> Methods <p>This study utilized survey data provided by the China Health and Retirement Longitudinal Study (CHARLS). Three analyses were performed: cross-sectional (<i>n</i> = 9,686), prospective (participants without baseline edentulism, <i>n</i> = 8,568), and trajectory analyses (TCBI trajectories and incident edentulism, <i>n</i> = 4,921). Logistic regression, Cox proportional hazards models, group-based trajectory modeling, and restricted cubic spline analyses were applied. Sensitivity analyses using cumulative TCBI during follow-up were also conducted.</p> Results <p>In the cross-sectional analysis, individuals in the highest TCBI tertile demonstrated a significantly lower risk of prevalent edentulism (adjusted OR = 0.80, 95% CI: 0.65–0.97). In the prospective analysis, higher TCBI levels were independently associated with a reduced risk of incident edentulism (adjusted HR = 0.85, 95% CI: 0.77–0.92). Trajectory modeling demonstrated that individuals with persistently high TCBI had the lowest risk of incident edentulism (adjusted HR = 0.59, 95% CI: 0.40–0.89). These associations remained robust in sensitivity analyses.</p> Conclusion <p>TCBI was consistently and inversely associated with edentulism across cross-sectional, prospective, and trajectory analyses. As a readily obtainable nutritional index, TCBI may have clinical utility for the early identification and risk prediction of edentulism.</p>