A method and apparatus are disclosed. In an example from the perspective of a User Equipment (UE), a signal to configure the UE to perform a Random Access Channel-less (RACH-less) handover to a second cell may be received in a first cell. The signal may comprise an uplink (UL) grant to be used in the second cell. The UL grant may be associated with a downlink (DL) signal. Whether to use the UL grant in the second cell may be determined based upon whether the DL signal is qualified.