Embodiments of this application disclose an inter-cell handover method and a controller to shorten a handover delay. The method includes: determining, by a first controller, a target cell, where the first controller is a controller of a source cell; sending, by the first controller, a pre-handover request to a second controller, where the second controller is a controller of the target cell, and the pre-handover request is used to instruct the second controller to allocate, to a terminal device, a first resource required for a cell handover; and sending, by the first controller, a handover command to the terminal device when determining that the terminal device meets a handover condition, where the handover command is used to instruct the terminal device to be handed over from the source cell to the target cell based on the first resource.