The multi-purpose beverage container holder supported tray assembly: includes a beverage container holder component and a tray component hingedly coupled to the beverage container holder component and provides one or more utilitarian support surfaces that may be used for various functions such as food and beverage placement, writing, and other activities where a stable, conveniently positioned surface is desired; and is adapted for use in theaters, stadiums, indoor and outdoor sports arenas, convention halls, home entertainment centers, and the like. The multi-purpose tray assembly is portable and removably supported in the seat arm beverage container holders (cup holders) normally found on the seating in the locations listed above. The position of the tray component of the tray assembly can be easily adjusted to suit the user and position the utilitarian support surface of the tray component in a location most convenient for the intended use.