Heart failure with preserved ejection fraction (HFpEF) has emerged as a major and growing public health challenge, accounting for nearly half of all heart failure cases worldwide. Once considered a milder form of heart failure, HFpEF is now recognised as a distinct, complex, and heterogeneous clinical syndrome associated with substantial morbidity, recurrent hospitalisations, impaired quality of life, and mortality rates comparable to heart failure with reduced ejection fraction (HFrEF). This review comprehensively examines the epidemiology, risk factors, pathophysiology, clinical presentation, diagnostic strategies, phenotypic heterogeneity, prognostic markers, and current management principles of HFpEF. Central to HFpEF pathogenesis are diastolic dysfunction, ventricular–vascular uncoupling, endothelial and microvascular dysfunction, systemic inflammation, and multiorgan involvement driven largely by cardiometabolic comorbidities such as hypertension, obesity, diabetes mellitus, atrial fibrillation, and chronic kidney disease. Diagnostic evaluation remains challenging due to preserved systolic function and symptom overlap with non-cardiac conditions, necessitating integrated approaches using echocardiography, biomarkers, and validated diagnostic algorithms such as H₂FPEF and HFA-PEFF scores. Growing recognition of HFpEF as a heterogeneous syndrome has shifted focus toward phenotyping and precision medicine, as conventional “one-size-fits-all” therapies have largely failed to demonstrate mortality benefit. Current management prioritises symptom relief, decongestion, and aggressive optimisation of comorbidities, with emerging evidence supporting phenotype-specific and multimodal strategies. Understanding HFpEF as a systemic, multifactorial disorder is essential for improving diagnosis, risk stratification, and therapeutic outcomes.