A ratiometric electrochemical sensor has been developed for highly sensitive and selective detection of bisphenol A. The assay strategy was based on the competitive host–guest interaction between poly-β-cyclodextrin/electroreduced graphene (Pβ-CD/EG) and Rhodamine B (RhB) probe or bisphenol A (BPA) target molecules. RhB can enter into the hydrophobic inner cavity of β-CD and shows an obvious oxidation peak on the Pβ-CD/EG modified glassy carbon electrode. In the presence of BPA, the RhB molecules are displaced by BPA because the host–guest interaction between β-CD and BPA is stronger than that between β-CD and RhB. As a result, the oxidation peak current of RhB (I RhB ) decreases and the oxidation peak current of BPA (I BPA ) increases correspondingly. The logarithmic value of I BPA /I RhB is linear with the logarithm of BPA concentration in the range of 1–6000 nM and the detection limit is 52pM (S/N=3). This strategy provides a new approach for sensitive detection of BPA, and has promising applications in the detection of organic pollutants in real environmental samples.