BACKGROUND: Gait speed is an independent prognostic factor in patients with heart failure (HF) and is recognized as a therapeutic target. Although a single cutoff of 0.98 m/s has been proposed based on post-discharge prognosis, the continuous relationship between gait speed and outcomes suggests the possible presence of multiple cutoffs. Identifying these thresholds may help establish stepwise, attainable goals for a broad range of older HF patients. This study aimed to determine whether additional prognostic gait speed cutoffs exist at discharge in older HF patients. METHODS: We conducted a secondary analysis of the J-Proof HF, comprising 7326 hospitalized patients aged ≥ 65 years with confirmed HF. The cohort was randomly divided into a derivation (60%) and a validation (40%) cohort. The primary outcome was a composite of all-cause death or HF readmission within 1 year. Gait speed cutoffs were identified in the derivation cohort using survival classification and regression tree (CART) analysis and validated in the validation cohort. RESULTS: Three prognostic cutoffs were identified (< 0.39, < 0.69, and < 1.00 m/s), defining four gait speed categories. Patients with slower gait speed were older, had more comorbidities, and poorer physical function. Gait speed category remained independently associated with outcomes (HR 1.21, 95% CI 1.13-1.30). CONCLUSIONS: This study established new prognostic gait speed cutoffs in older HF patients, which may help set individualized physiotherapy goals based on patient mobility. TRIAL REGISTRATION: ClinicalTrials.gov identifier: UMIN000047893.