The COVID-19 pandemic has had a significant impact on all facets of life and has exacerbated many challenges faced by people living with tuberculosis (TB). This study aimed to assess the health-related quality of life (HRQoL) of TB patients in Guinea during the COVID-19 pandemic. A mixed-methods study was conducted using two validated psychometric tools to assess HRQoL and qualitative interviews among TB patients enrolled in treatment at three centers in Conakry, Guinea. Multinomial logistic regression was used to identify factors associated with the deterioration of HRQoL. We included 439 participants in the study, among whom 44% and 31% experienced pain and anxiety, respectively. We found that an increase in the number of household members and the distance from participants’ residence to the health centre were significantly associated with lower HRQoL. Qualitative interviews highlighted nutritional and financial concerns which were exacerbated during COVID-19 pandemic and beliefs that the Guinean Government’s assistance plan was insufficient. This study supports the implementation of specific relief plans for TB patients which includes nutritional and psychological support, especially those whose movements are limited by travel restrictions, impeding access to TB care, reducing work opportunities and exacerbating financial needs and stress.