A device for movably mounting a storage container in relation to the storage bed of a pickup truck. The device includes a container support frame with a mounting member configured to be fixedly secured in relation to the pickup truck storage bed, and a lift arm having a first end coupled to the container support frame for pivotal movement about a first pivot axis and a second end configured to be coupled to the storage container for pivotal movement about a second pivot axis. The second end of the lift arm is movable along an arcuate path about the first pivot axis between a stowed position in which the storage container is disposed between the side rails and an extended position in which the storage container is disposed above a side rail. The storage container is pivotable about the second pivot axis to maintain an upright orientation in the stowed and extended positions, providing a variety of convenient access and storage options. Also, the frame can be confined to a very small portion of the storage bed or hidden within existing components of the storage bed to allow substantially unimpeded top and rear access to the storage bed.