Significance Rifampicin (Rif) is an antibiotic that targets bacterial RNA polymerase (RNAP). The search for new antibiotics against proven targets is one approach to combat multidrug-resistant tuberculosis (TB), a global threat. Here, we characterized the effects of the antibiotic sorangicin A (Sor) on a Rif-resistant (Rif ^R ) RNAP found in clinically isolated Rif ^R strains. Sor binds in the same pocket and inhibits wild-type RNAP by the same mechanism as Rif. However, Sor inhibits Rif ^R RNAPs by a distinct mechanism, providing a new target for drug design. Intriguingly, Sor displays a better pharmacokinetic profile compared to rifamycins, which is important for development of inhibitors to treat TB patients suffering from comorbidities. These results inform approaches toward drug development against antibiotic-resistant targets.