Riboflavin (RB) plays a pivotal role in cell growth and various biochemical reactions in the human body. Low level of RB leads to various health related issues and hence it is imperative to develop a sensitive and selective method for determination of RB. Electrochemical property of RB at poly-l-leucine modified carbon paste electrode (PLMCPE) was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in 0.2 M phosphate buffer solution (PBS) of an optimum pH of 6.5. Favourable interaction between l-leucine (l-leu) film and RB enhance the redox current response in comparison with bare carbon paste electrode (BCPE). The process at the exterior of the electrode was noticed to be reversible and diffusion controlled in the potential window of − 0.8 to 0 V/s. The surface characterisation of fabricated PLMCPE was accomplished by Field emission scanning electron microscopy (FE-SEM) and Electronic impedance spectroscopy (EIS). Parameters like electrochemical active surface area of the sensor, number of electrons transferred, surface concentration and heterogeneous rate constant were calculated. Under optimised condition DPV and CV divulge a notable linear relationship in between the oxidation peak current of RB and concentration of RB with a detection limit (LOD) of 3.4 × 10–8 M and 4.02 × 10–8 M respectively. Various interferant metal ions were used to investigate the interference effect and was found that the method is compelling, selective and sensitive towards detection of RB. The performance of PLMCPE was triumphantly tested for the detection of RB in vitamin capsules by DPV and the excellent recovery proves that the proposed method can be constructively used for real sample analysis.