To explore, in a hypothesis-generating framework, the relationship between heel fat pad thickness (HFPT), measured by plain radiography, and clinical parameters of disease severity and disability in systemic sclerosis (SSc), and to assess the specificity of HFPT atrophy by comparing SSc patients with healthy controls and disease controls. In this single-center, cross-sectional study, 98 SSc patients were enrolled. HFPT was measured on lateral foot radiographs with excellent reliability (intra-observer ICC = 0.96; inter-observer ICC = 0.94, 95% CI: 0.88–0.97). Clinical data included demographics, disease subtype, modified Rodnan Skin Score (mRSS), Medsger Severity Score (MSS), and Health Assessment Questionnaire (HAQ). Pearson and Spearman correlations, partial correlation analysis, multivariable linear regression, and exploratory logistic regression with ROC analysis were performed. Mean HFPT was 18.65 ± 2.70 mm in SSc patients. HFPT demonstrated strong negative correlations with mRSS (Pearson r = − 0.918, 95% CI [− 0.944, − 0.879]; Spearman ρ = −0.973, 95% CI [− 0.982, − 0.960], both p < 0.001) and MSS (both p < 0.001), but no correlation with HAQ (r = 0.036, p = 0.725). Patients with pulmonary involvement had significantly thinner HFPT (17.60 ± 1.89 mm vs. 22.18 ± 1.35 mm, p < 0.0001; Cohen’s d = 2.74). In multivariable linear regression, mRSS explained 84.71% of HFPT variance (unstandardized β = −0.169, p < 0.001). Critically, in multivariable logistic regression adjusting for mRSS, HFPT was not an independent predictor of pulmonary involvement (OR = 0.062, 95% CI [0.003, 1.468], p = 0.18), indicating mediation through shared fibrotic burden. HFPT reflects overall fibrotic burden rather than functional disability or pulmonary-specific involvement. These hypothesis-generating findings require external validation in multicenter cohorts before clinical application. HFPT should be regarded as an exploratory imaging marker of systemic fibrotic burden in SSc, not as a clinically actionable diagnostic tool.