Background: Tuberculosis is the world’s deadliest infectious disease and a leading cause of death in Nigeria. The availability of a functional healthcare system is critical for effective TB service delivery and attainment of national and global targets. This study was designed to assess readiness for TB service delivery in Oyo and Anambra states of Nigeria.

Methods: This was a facility-based study with a mixed-methods convergent parallel design. A multi-stage sampling technique was used to select 42 primary, secondary, and tertiary healthcare facilities in two TB high burden states. Data were collected using key informant interviews, a semi-structured instrument adapted from the WHO Service Availability and Readiness Assessment tool and facility observation using a checklist. Quantitative data were analysed using descriptive and inferential statistics while qualitative data were transcribed and analysed thematically. Data from both sources were integrated to generate conclusions.

Results: The domain score for basic amenities in both states was 48.8%; 47.0% in Anambra and 50.8% in Oyo state with 95% confidence interval [− 15.29, 7.56]. In Oyo, only half of the facilities (50%) had access to constant power supply compared to 72.7% in Anambra state. The overall general service readiness index for both states was 69.2% with Oyo state having a higher value (73.3%) compared to Anambra with 65.4% (p = 0.56). The domain score for availability of staff and TB guidelines was 57.1% for both states with 95% confidence interval [− 13.8, 14.4]. Indicators of this domain with very low values were staff training for the management of HIV and TB co-infection and training on MDR -TB. Almost half (47.6%) of the facilities experienced a stock out of TB drugs in the 3 months preceding the study. The overall tuberculosis-specific service readiness index for both states was 75%; this was higher in Oyo (76.5%) than Anambra state (73.6%) (p = 0.14). Qualitative data revealed areas of deficiencies for TB service delivery such as inadequate infrastructure, poor staffing, and gaps with continuing education on TB management.

Conclusions: The weak health system remains a challenge and there must be concerted actions and funding by the government and donors to improve the TB healthcare systems.