The lattice degree of freedom has been utilized to pursue exotic functionalities in complex oxide heterostructures via various external stimuli, such as light, electric field, and magnetic field. Here, the epitaxial heterostructures composed of photostrictive SrRuO 3 thin films and ferroelectric 0.7Pb(Mg 1/3 Nb 2/3 )O 3 -0.3PbTiO 3 single-crystal substrates are fabricated to investigate the light and electric field co-control of lattice order in resistance switching. The electric-field-induced strainmediated electroresistance response can be effectively tuned by light illumination. This, together with the electric-field-tunable photoresistance effect, demonstrates strong correlation between the light and the electric field, which is essentially mediated by strain-driven lattice-orbital coupling. Our findings provide a platform for realizing multi-field tuning of the lattice degree of freedom and the resultant functionalities in complex oxide heterostructures. Published by AIP Publishing.