Background: Association between age, frailty, and the receipt of thrombectomy for acute ischemic stroke is not well understood. Methods: We conducted a population-based retrospective cohort study of adults hospitalized with an ischemic stroke between 2018 and 2022 in Ontario, Canada. In sex-stratified models, we studied whether frailty (based on hospital-based frailty index: mild, moderate and severe) modified the association between age and thrombectomy by using interaction terms in multivariable modified Poisson regression models. Results: Among 59,346 patients (median age 75 years, 47.0% female) with ischemic stroke 4,454 (7.5%) received thrombectomy, with no sex differences in this treatment. In both sexes, increasing age was associated with decreased use of thrombectomy (adjusted risk ratio [aRR] for every 5-year increase, female = 0.91; 0.89-0.92; male = 0.92; 0.90-0.94). Frailty was not associated with thrombectomy in females (aRR high vs. low frailty = 0.86; 0.68-1.10) or males (aRR high vs. low frailty = 1.10; 0.87-1.39). Furthermore, the interaction between age and frailty was not significant for either sex. Conclusions: Frailty was not associated with thrombectomy in either sex, and it did not modify the association between age and thrombectomy, suggesting a greater role of chronological age compared to frailty in thrombectomy decisions in ischemic stroke patients.