A communication device for handling mobility management includes a storage unit for storing instructions and a processing circuit coupled to the storage unit. The processing circuit is configured to execute the instructions stored in the storage unit. The communication device performs attaching to a first network and not having an active Packet Data Network (PDN) connection with the first network; selecting a second network after attaching to the first network; initiating an attach procedure to the second network, if the second network does not support an attach without the PDN connection establishment; and initiating a tracking area update (TAU) procedure to the second network, if the second network supports the attach without the PDN connection establishment.