Understanding diffusion in alumina is a long-standing challenge in ceramic science. The present article applies a novel combination of metadynamics and kinetic Monte Carlo simulation approaches to the investigation of oxygen vacancy diffusion in alumina. Three classes of diffusive jumps with different activation energies were identified, the resulting diffusion coefficient being best fitted by an Arrhenius equation having a pre-exponential factor of 7.88 x 10-2 m2 s-1 and an activation energy of 510.83 kJ mol-1. This activation energy is very close to values for the most pure aluminas studied experimentally (activation energy 531 kJ mol-1). The good agreement indicates that the dominating atomic-scale diffusion mechanism in alumina is vacancy diffusion.