A near-field communication (NFC) system may include an NFC tag comprising a memory configured to store geo-position data corresponding to a geographic position of the NFC tag, and a first NFC sensor coupled to the memory and configured to initiate a transaction based upon NFC communications. The NFC system may further include a mobile wireless communications device comprising a second NFC sensor and a controller coupled thereto. The controller may be configured to establish NFC communications with the first NFC sensor when in proximity thereto and retrieve the geo-position data therefrom, authenticate a geographic position of the NFC tag based upon the retrieved geo-position data, and perform the transaction with the NFC tag if the geographic position of the NFC tag is authenticated.