Background: There is no known therapy with proven efficacy for improving clinical outcomes in elderly patients with heart failure (HF) and preserved ejection fraction (HFpEF). In this study, we aimed to evaluate the efficacy of tolvaptan (TLV) in elderly HFpEF patients. Methods: This retrospective observational study involved 100 consecutive elderly HFpEF patients hospitalized at the Nagoya Heart Center, Japan. Inclusion criteria were: (1) patients aged ≥75 years; (2) first hospitalization secondary to HF; (3) received medical therapy for HF, without invasive treatment; and (4) clinical follow-up for >6 months after discharge. The primary endpoint was rehospitalization due to worsening HF, and the secondary endpoint was worsening renal function (WRF) during hospitalization and at 6 months after discharge. Sixty background-matched HFpEF patients were divided into 2 groups: with TLV therapy (TLV (+), n = 29) and without TLV therapy (TLV (–), n = 31). In the TLV (+) group, TLV therapy was continued after discharge. Clinical outcomes of these patients were evaluated. Results: Bed rest period and length of hospital stay were significantly shorter in the TLV (+) group than in the TLV (−) group. The dose of loop diuretics, mean serum creatinine levels, and incidence of WRF development were significantly lower in the TLV (+) group. Incidence of rehospitalization was also significantly lower in the TLV (+) group (log-rank test; p = 0.018). The multivariate logistic regression analysis demonstrated that TLV therapy reduces the incidence of rehospitalization in elderly patients with HFpEF. Conclusions: TLV therapy reduced the bed rest period, length of hospital stay, and rate of rehospitalization without WRF in elderly HFpEF patients, suggesting that TLV could represent an effective therapy for this group of patients.