Nanodiscs with ZnFe2O4 core and Ag-deposited ZnO shell have been synthesized by hydrothermal method. Scanning electron microscopy (SEM) shows the morphology as nanodiscs. X-ray diffractometry (XRD), selected area electron diffractometry (SAED) and Raman spectroscopy reveal cubic ZnFe2O4, hexagonal ZnO and face centered cubic Ag as the constituents of the synthesized nanodiscs. Energy dispersive X-ray spectroscopy (EDS) provides the atomic percentage of Ag as 0.6. High resolution transmission electron microscopy (HRTEM) displays the core–shell structure of the synthesized nanodiscs. The specific surface area, pore volume and pore radius of the nanodiscs are 26.83 m2 g−1, 0.082 cm3 g−1 and 4.88 nm, respectively. The charge-transfer resistance (RCT) of precursor ZnFe2O4 nanoparticles, determined by solid state impedance spectroscopy, is very much smaller than that of pristine ZnO and ZnFe2O4/Ag–ZnO and the RCT of ZnFe2O4/Ag–ZnO is larger than that of ZnO. The capacitance (C) of ZnFe2O4/Ag–ZnO is very much smaller than that of ZnFe2O4 and ZnO and the C of ZnFe2O4 is much larger than that of ZnO. ZnFe2O4/Ag–ZnO nanodiscs as well as ZnFe2O4 nanopowder are superparamagnetic. ZnFe2O4/Ag–ZnO exhibits surface plasmon resonance (SPR) in the visible region. The emission spectrum of ZnFe2O4/Ag–ZnO is similar to that of pristine ZnO and shows violet, blue, blue–green and green emissions due to different crystal defects in ZnO lattice. The synthesized nanodiscs display visible light photocatalysis, degrade dye completely and are reusable visible light photocatalyst. The mechanism of visible light photocatalysis is addressed.