India accounts for one-quarter of the world's TB cases. Despite efforts to engage the private sector in India's National TB Elimination Program, informal healthcare providers (IPs), who serve as the first contact for a significant TB patients, remain grossly underutilised. However, considering the substantial evidence establishing IPs' role in patients' care pathway, it is essential to expand the evidence base regarding their knowledge in TB care. We conducted a cross-sectional study in the Birbhum district of West Bengal, India. The data were collected using the TB vignette among 331 IPs (165 trained and 166 untrained). The correct case management was defined following India's Technical and Operational Guidelines for TB Control. Overall, IPs demonstrated a suboptimal level of knowledge in TB care. IPs exhibited the lowest knowledge in asking essential history questions (all four: 5.4% and at least two: 21.7%) compared with ordering sputum test (76.1%), making a correct diagnosis (83.3%) and appropriate referrals (100%). Nonetheless, a statistically significant difference in knowledge (in most domains of TB care) was observed between trained and untrained IPs. This study identifies gaps in IPs' knowledge in TB care. However, the observed significant difference between the trained and untrained groups indicates a positive impact of training in improving IPs' knowledge in TB care.