Background and Objectives: This cross-sectional study examined associations between kinanthropometric indicators and lower-body force-time performance in 34 professional male boxers. Athletes were recruited by convenience sampling; no a priori sample-size calculation was performed. Methods: CMJ, countermovement rebound jump, and isometric-squat outcomes were assessed using a force platform. Three missing derived anthropometric estimates were recalculated from recorded measurements, and site-specific corrected-girth calculations, the Rocha bone-mass equation, and the Kerr adipose-mass input were corrected following confirmation by the study anthropometry investigator. A matrix of 117 Spearman correlations was evaluated with Benjamini–Hochberg false-discovery-rate adjustment. Results: CMJ peak force was correlated with BMI (rho = 0.697), body mass (rho = 0.663), corrected girths (rho = 0.622), estimated muscle mass (rho = 0.573), and adipose mass (rho = 0.508). Isometric-squat peak force was correlated with corrected girths (rho = 0.651), estimated muscle mass (rho = 0.638), sitting height (rho = 0.547), and estimated bone mass (rho = 0.521). Thirteen of 117 exploratory associations survived FDR correction. Conclusions: In this exploratory sample, observed relationships with absolute force tended to be larger than those with relative, ballistic, or time-dependent outputs, but formal differences between dependent correlations were not tested. The observed associations, including those based on anthropometric tissue-mass estimates, do not establish causal or body-mass-independent effects.