Some demonstrative embodiments include devices, systems of securing communications of a User Equipment (UE) in a Wireless Local Area Network (WLAN). For example, a UE may include a WLAN transceiver; a cellular transceiver to communicate with an evolved Node B (eNB) of a cellular network; and a controller to determine a UE security key based on a cellular security key corresponding to the eNB, and to establish a connection with a WLAN access device based on the UE security key.