Interfacial engineering is important for ferroelectric thin-film heterostructures because of the modulation of boundary conditions of the spontaneous polarizations and their switching behaviors, which are essential for ferroelectric electronics. In this work, we study the effects of interfacial buffering layer, 5-nm-thick SrTiO₃ (STO), on the imprint and domain switching of epitaxial Pt/Pb(Zr,Ti)O₃/SrRuO₃ (SRO) thin-film heterostructures and capacitors. By buffering the ultrathin SrTiO₃ layer at the Pb(Zr,Ti)O₃ surface, the imprint effect can be dramatically alleviated as observed in the piezoresponse force microscopy (PFM)-measured domain structures and polarization–electric field hysteresis loops in thin-film capacitors. However, when the SrTiO₃ layer is buffered at the Pb(Zr,Ti)O₃/SrRuO₃ interface, the imprint effect is slightly increased. These phenomena are explained based on the band alignments among the Pt and SrRuO₃ electrodes and the Pb(Zr,Ti)O₃ layer associated with the existence of oxygen vacancies in the SrTiO₃ layer. With the reduction of imprint effect, the domain switching dynamics are also improved in the SrTiO₃-buffered Pb(Zr,Ti)O₃ capacitor, in which the switching activation field is decreased by about 45.3% in comparison with that of the pristine capacitor. These results facilitate the design and optimization of ferroelectric devices with the improvements in domain configurations, switching behaviors and band alignments.