Some demonstrative embodiments include devices, systems of securing communications of a User Equipment (UE) in a Wireless Local Area Network (WLAN). For example, a cellular node may transmit to a UE a cellular message including a UE security key, and a WLAN access device may communicate with the cellular node security information including the UE security key. The WLAN access device may communicate with the UE based on the UE security key, e.g., to authenticate the UE and/or encrypt communications with the UE.