Background: Real-world evidence pertaining to high-risk Non-Muscle Invasive Bladder Cancer (NMIBC) is limited. We aimed to describe real-world treatment patterns and outcomes of this study population within a Canadian setting. Methods: A retrospective cohort study was conducted by linking various population-based administrative datasets from a large Canadian province. The study population consisted of all individuals ≥ 18 years who were diagnosed with Tis or high-grade Ta/T1 NMIBC in Alberta, Canada between 2010-2019. High-grade disease was defined using the WHO 1973 system. Individuals who initiated BCG therapy were classified as having received adequate induction therapy if they completed 5+ cycles. BCG unresponsive was defined as receipt of TURBT, intravesical chemotherapy, cystectomy, or radiation within 1 year of the last BCG dose. Overall survival (OS), cystectomy-free survival (CFS), progression-free survival (PFS), and healthcare resource utilization (HCRU) were examined from the time of being classified as BCG unresponsive following adequate induction therapy. CFS was defined as time until death or radical cystectomy and PFS was defined as time until death or disease progression. Disease progression was classified using a proxy based on subsequent receipt of cystectomy, systemic therapy, or radiation. Kaplan-Meier survival curves were estimated for OS, CFS, and PFS and the mean number of healthcare encounters within each year of follow-up were estimated for HCRU. Results: 5369 individuals were diagnosed with NMIBC in Alberta between 2010-2019, of whom 2679 (49.9%) had Tis or HG Ta/T1 disease at initial diagnosis. Among individuals with high-risk NMIBC, 1044 (39%) initiated BCG therapy. 885 (84.8%) individuals received 5+ BCG doses. Despite receiving adequate induction treatment, 249 (28.1%) individuals became unresponsive. The mean age at BCG unresponsive was 72.9 years and 213 (58.5%) were males. Among those who were BCG unresponsive, 25.7% underwent radical cystectomy (median time to cystectomy: 4.4 months, IQR: 1.7 to 8.2). Median OS was 50.7 months (95% CI: 37.2-65.5), CFS was 22.4 months (18.9-31.1), and PFS was 14.4 months (11.6-20.9). Within the first year of becoming BCG unresponsive, individuals spent an average of 6.2 days in hospital, had 28.8 visits with healthcare practictitioners, and had 2.2 emergency and 13.6 non-emergency encounters with ambulatory care services. Conclusions: A considerable proportion of individuals with high-risk NMIBC became unresponsive to BCG therapy despite adequate treatment. The time from becomining BCG unresponsive to radical cystectomy was relatively short. These findings highlight an unmet need in this patient population for alternative therapeutic options.