PURPOSE: Understanding the influence of frailty on health-related quality of life (HRQoL) in older individuals experiencing chronic low back pain can provide valuable insights into the impact of frailty. Therefore, the aim of our study is to assess how different frailty statuses among older outpatients with chronic low back pain affect their HRQoL. METHODS: Patients aged 60 and above with chronic low back pain were recruited from March 2022 to February 2023. Frailty was assessed via the frailty phenotype questionnaire, and HRQoL was evaluated using the EQ-5D-5L. Multiple regression models were used to explore the influence of frailty status on the EQ-5D-5L index and EQ-VAS. Logistic regression was used to determine odds ratios for the impact of frailty status on belonging to the lowest EQ-5D-5L index quartile. RESULTS: A total of 1,054 participants were classified into robust (29.8%), pre-frail (47.7%), and frail (22.5%) groups. Frailty was significantly associated with declining HRQoL. Pre-frail and frail statuses were inversely linked to the EQ-5D-5L index, with significantly higher odds of scoring in the lowest quartile compared to robust individuals. Stratification analysis identified sex as an effect modifier, emphasizing a more substantial association between frailty and the lowest EQ-5D-5L index quartile in female patients. CONCLUSIONS: A significant association exists between frailty and reduced HRQoL in patients with chronic low back pain. This association was predominant in female patients. Furthermore, considering the dynamic nature of frailty, early detection and effective interventions targeting pre-frailty are essential to delaying the transition to full frailty and improving HRQoL.