The cell envelope-associated proteins of Mycobacterium species play critical functions in the physiology and pathogenicity of these microorganisms. Because the determination of their subcellular localization and transmembrane topology is often critical to the understanding of their function, we investigated whether the Green Fluorescent Protein (GFP) could be used as a reporter to probe protein localization and map the topology of inner membrane proteins directly in intact mycobacterial cells. To this end, two GFP-based mycobacterial reporter plasmids were engineered and their functionality validated using a variety of membrane-associated, exported and cytosolic proteins.