A secure package delivery system comprises a lockable container configured for securement to a movable door or exterior wall of a building structure. The container includes a walled body and openable lid. A vertically and horizontally adjustable dolly handle assembly is slideably coupled to a rear of the body and operable to form an adjustable gap for receiving a portion of the door to trap and secure the container in place. The handle assembly is lockable in place to the container and in vertical position by a crank mechanism operated via a lever. The container further includes a movable securement aperture in the handle assembly and wall pin which permits securing the container to a wall via operation of handle assembly and crank mechanism. A movable latch operated by the crank mechanism secures the wall pin in the securement aperture to prevent removal of the container.