Heart failure with preserved ejection fraction (HFpEF) is a major health care problem, with no treatment available that significantly reduces mortality. HFpEF is a phenotypically diverse syndrome, which creates difficulties in establishing an accurate diagnosis, determining prognosis, and developing effective management strategies. The number of serum biomarkers being investigated to further our understanding of HFpEF is rapidly expanding. In this review, we critically appraise the current clinical utility of biomarkers in HFpEF, particularly for pathophysiological pathways involving cardiomyocyte stretch, injury, fibrosis, remodelling, systemic inflammation, and renal dysfunction. Guideline-based clinical indications for biomarker testing in HFpEF and their limitations are discussed. Investigative strategies including the use of multi-biomarker panels and standardisation of research methodologies may prove useful in developing biomarkers for HFpEF in the future.