Aims: Cardiovascular-kidney-metabolic (CKM) multimorbidity is prevalent among individuals with heart failure (HF), but whether cardiac structure and function, clinical outcomes, and treatment response to sacubitril/valsartan vary in relation to CKM status is unknown. Methods and results: In this PARAGON-HF post-hoc analysis, we evaluated the impact of CKM multimorbidity (atherosclerotic cardiovascular [CV] disease, chronic kidney disease, and type 2 diabetes) on cardiac structure and function, clinical outcomes, and treatment effects of sacubitril/valsartan versus valsartan. The primary outcome was a composite of total HF hospitalizations and CV death. Secondary outcomes included the individual components of the primary outcome and a composite kidney outcome (sustained estimated glomerular filtration rate reduction of ≥50%, end-stage kidney disease, or kidney-related death). At baseline, 35.2% had one CKM condition, 33.3% had two, 15.9% had three, and only 15.6% had HF alone. CKM multimorbidity was associated with higher septal and posterior wall thickness, lower global longitudinal strain, higher E/e', and worse right ventricular function. Total HF hospitalizations or CV death increased with greater CKM multimorbidity, with the highest relative risk observed with three CKM conditions (rate ratio 3.06, 95% confidence interval 2.33–4.03), compared with HF alone. Treatment effects of sacubitril/valsartan were consistent irrespective of the number of CKM conditions for the primary endpoint (p_interaction = 0.75), CV death (p_interaction = 0.82), total HF hospitalizations (p_interaction = 0.67), and the composite kidney endpoint (p_interaction = 0.99). Conclusions: Cardiovascular-kidney-metabolic multimorbidity was common in PARAGON-HF and associated with adverse changes in cardiac structure and function and with a stepwise increase in risk of clinical outcomes. Treatment effects of sacubitril/valsartan were consistent irrespective of CKM burden. Clinical Trial Registration: ClinicalTrials.gov NCT01920711.