We report on the fast wavelength switching in V-cavity laser (VCL) with quantum well intermixed tuning section. The laser wavelength can be switched between 32 channels at 100 GHz spacing using a single electrode control. The fabrication process involves a quantum well intermixing (QWI) process using KrF laser irradiation and rapid thermal annealing (RTA). The tuning current is less than 40 mA, much lower than previously demonstrated tunable VCL based on electro-thermal-optic effect. The wavelength switching is also faster by three orders of magnitude. The dynamic switching characteristics between two channels with different numbers of intermediate channels are investigated. It shows that the switching time is about 1 ns between adjacent channels and increases up to 12 ns with increasing number of intermediate channels.