Background: The COVID-19 pandemic's first wave and subsequent lockdowns disrupted global healthcare systems, significantly impacting essential services including tuberculosis (TB) care. Non-adherence to anti-TB drugs is a critical concern, leading to treatment failure, drug resistance, and increased morbidity and mortality. This study assessed the rate and determinants of nonadherence to TB treatment among patients at TB centers during the first wave of the pandemic. Material and Methods: A cross-sectional study was conducted from June 15 to July 30, 2020, involving 255 TB patients at three centers in Mogadishu. Data were gathered using the Morisky Medication Adherence Scale-8 (MMAS-8) through structured interviews and analyzed using descriptive statistics and binary logistic regression. Results: The study found a 34.5% non-adherence rate during the pandemic. Key reasons for non-adherence included forgetting to take medication (33%), feeling well (29%), experiencing side effects (18%), and fear of contracting COVID-19 (16%). Significant factors associated with non-adherence were age groups 25-34 years (OR = 2.96, p = 0.024) and 35-44 years (OR = 4.55, p = 0.005), unemployment (OR = 2.57, p = 0.037), smoking (OR = 3.49, p = 0.029), tobacco use (OR = 4.15, p = 0.034), proximity to a health facility (OR = 0.44, p = 0.033), perception of healthcare providers as very friendly (OR = 0.24, p = 0.031) or friendly (OR = 0.45, p = 0.023), being in the continuous treatment phase (OR = 3.2, p < 0.001), and experiencing adverse treatment effects (OR = 2.42, p = 0.003). Conclusion: Non-adherence to anti-tuberculosis treatment was notably high in Mogadishu during the first wave of the pandemic, necessitating targeted interventions to improve adherence.