A model-independent study of CP violation in B0 → DK∗0 decays is presented using data corresponding to an integrated luminosity of 9 fb−1 collected by the LHCb experiment at centre-of-mass energies of √s = 7, 8 and 13 TeV. The CKM angle γ is determined by examining the distributions of signal decays in phase-space bins of the self-conjugate D → K0 Sh+h− decays, where h = π, K. Observables related to CP violation are measured and the angle γ is determined to be γ = (49+22 −19)◦. Measurements of the amplitude ratio and strong-phase difference between the favoured and suppressed B0 decays are also presented.