Methods, systems, and media for user authentication in hybrid online and real-world environments are disclosed. In one example, a method comprises providing a real-world environment including a display of physically retrievable items available for purchase, detecting the presence of a user device associated with a user in the real-world environment, and storing identity data received from the user device. Interest data for one of the physically retrievable items is identified based on sensed biometric data of the user and an online offering for a comparable online item is automatically implemented without manual operation of the user device. A user identification associated with an online account is derived based on the stored identity data received from the user device and the online offering for the item comparable to the physically retrievable item is provided to the online account associated with the user identification.