In this work, a new sensitive voltammetric method for the determination of rifampicin without time-consuming preconcentration is presented. The objective was to develop a simple, fast and sensitive voltammetric procedure for the analysis of rifampicin in pharmaceutical products. The cyclic renewable mercury film silver-based electrode (Hg(Ag)FE) was applied as a working electrode for this purpose. The optimal conditions for the determination of rifampicin were defined, in terms of the composition of supporting electrolyte (including pH) and instrumental parameters (potential and time of deposition, step potential, pulse height). The method was validated resulting in a satisfactory linearity range of 0.4–250.0 µgmL; the limits of detection and quantification are 0.12 µgmL and 0.4 µgmL, respectively; and the repeatability of the method expressed as RSD is 4.1% (n = 6) with a surface area of 10.9 mm. The proposed method was successfully applied in the analysis of rifampicin in simple and composed pharmaceutical formulations.