In this study, we investigate the effect of magnetic field annealing on the magnetostriction and deflection properties of polycrystalline CoFe2O4 thin films grown on Si(1 0 0) substrates by pulsed laser deposition. Prior to the field-annealing process, both structural and magnetic properties of the CoFe2O4 films were optimized through controlling the oxygen pressures from 7 to 13.3 Pa. A good combination of saturation magnetization (195 emu/cm3) and coercivity (690 Oe) was obtained for the CoFe2O4 films grown at 9.0 Pa. These films when subjected to field-annealing demonstrated improved magnetostriction (91 micro-strain) and deflection (730 nm) properties, as compared to the conventionally annealed counterparts. The observed enhancement in the magnetostriction and deflection in the CoFe2O4 films is hypothesized to both domain wall rotation and movement facilitated by the field-annealing process. © 2018 Elsevier B.V.