Abstract Background and Aims Frailty prevalence is notably high among older hemodialysis patients, correlating with poorer prognoses. Prior smaller-scale studies have underscored the benefits of various exercise interventions in individuals with Chronic Kidney Disease and those receiving dialysis treatments. Addressing frailty in older hemodialysis patients by exercise therapy is crucial for healthcare professionals aiming to enhance patient outcomes. Despite this, a standardized exercise therapy protocol for this demographic has not been broadly implemented in clinical practice. Our study sought to evaluate the impact of intradialytic resistance exercise programs on the prognosis of frail individuals undergoing hemodialysis. Method This retrospective, multicenter, non-randomized clinical trial encompassed 2006 participants (mean age 70.1±11.7 years) from 17 outpatient clinics within the Kaikoukai Medical Group. Enrollment spanned from April to December 2018, with patients stratified according to baseline frailty levels, determined by the Japanese Frailty Criteria for the Diagnosis of Frailty in the Elderly. In this study, patients meeting the criteria for frailty or pre-frailty, as defined by the Japanese Criteria for Health and Social Services (J-CHS), were collectively classified as 'frail’. Participants were invited to join a voluntary exercise program during dialysis, which included stretching and four types of resistance exercises using elastic tubes. The cohort was divided into four groups based on their frailty status and participation in the exercise program. Patient outcomes were monitored until either death or the study's conclusion in December 2021. Kaplan-Meier and log-rank analyses were utilized to assess prognostic differences among the groups, with significance levels adjusted using the Bonferroni correction. Ethical approval was granted by the Nagoya Kyoritsu Hospital's ethical committee. Results The study comprised 112 non-frail exercising, 398 frail exercising, 205 non-frail non-exercising, and 1287 frail non-exercising patients. Over the study period (median 25 months), mortality was recorded in 338 (16.9%) patients, including 8 (7.1%) non-frail exercising, 50 (12.6%) frail exercising, 16 (7.8%) non-frail non-exercising, and 264 (20.5%) frail non-exercising participants. Prognostic analysis revealed that the frail non-exercising group had a significantly poorer prognosis than both the non-frail exercising and non-frail non-exercising groups, as well as the frail exercising group (p<0.05). Conclusion This investigation is pioneering in establishing a link between intradialytic resistance exercise interventions and prognosis in frail patients. The findings indicate that, although frail patients inherently face a more challenging prognosis, participation in intradialytic exercise can yield substantial improvements. Therefore, clinicians are encouraged to advocate for exercise therapy as a means to enhance prognosis in frail patients undergoing hemodialysis.