Numerical calculations of various corrections to the g factor of Li-like ions were performed. The interelectronic-interaction correction of order 1/Z² and higher was evaluated using the configuration-interaction Dirac-Fock method. The one-electroon quantum electrodynamics correction of first order in α is obtained by employing the recent results for the self-energy term and by evaluating the vacuum-polarization contribution. The correction to the Dirac g-factor value due to the extended nuclear size is relatively simple.