Heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) often coexist and exacerbate each other through left atrial remodeling, increased filling pressures, inflammation, obesity, renal dysfunction, endothelial dysfunction, and impaired exercise tolerance. Recent data have shifted treatment from symptomatic therapy alone to phenotype-targeted therapy. Significant developments include the use of first-line sodium-glucose cotransporter-2 (SGLT2) inhibitors, recent validation of non-steroidal mineralocorticoid receptor antagonists, the utility of GLP-1/GIP- targeted weight-loss therapy for obesity-associated HFpEF, and increased proactive approaches to rhythm control in AF. The effect of HFpEF on AF is bidirectional and clinically important. HFpEF leads to atrial fibrosis and raised filling pressures, while AF aggravates diastolic dysfunction via atrial contraction loss and irregular ventricular filling. Modern management thus depends on an integrated approach targeting congestion, metabolic failure, atrial disease, obesity, hypertension, diabetes mellitus, renal dysfunction and thromboembolic hazard. This review provides an overview of recent pathophysiologic advances, diagnostic and treatment considerations, alongside recent and ongoing therapeutic developments for HFpEF followed by AF, including updates on the ESC guideline and large clinical trials.