A communication device for handling a cellular-wireless local area network (cellular-WLAN) aggregation (CWA) comprises a storage device for storing instructions and a processing circuit coupled to the storage device. The processing circuit is configured to execute the instructions stored in the storage device. The instructions comprise establishing a radio resource control (RRC) connection to a cellular network; receiving a first RRC message configuring a CWA for a radio bearer from the cellular network on the RRC connection; enabling data handling for the radio bearer in response to the first RRC message; receiving an RRCConnectionRelease message or a MobilityFromEUTRACommand message on the RRC connection from the cellular network; and disabling the data handling for the radio bearer and not performing data recovery for the radio bearer, in response to the RRCConnectionRelease message or the MobilityFromEUTRACommand message.