A garbage disposal installation tool is provided that is adapted to support a garbage disposal from its upper opening and through the sink drain, whereby the disposal unit is supported from above while the installer secures the unit to the sink drain. The device comprises a tool body having an elongated, threaded rod with an upper end and a lower end. The upper end comprises a handle, while the lower end comprises a pivotable garbage disposal support member adapted to support the disposal unit from its upper opening and from the interior thereof. Along the threaded rod is a sink drain bridge element that is adapted to bear against the upper surface of a sink drain and support the tool body and the disposal unit therefrom. The bridge element is threaded to the elongated rod and positionable along its length to elevate the disposal unit by rotating the handle.