A security lighting system is provided for convenient mounting to a standard electrical junction box. The security light fixture includes a housing, a cantilevered arm extending from the housing, and a back plate on an end of the cantilevered arm. The back plate has a reinforced attachment structure capable of supporting the bending moment of the heavy, cantilevered light structure. The attachment structure may include, for example, a reinforced cone. The back plate and cantilevered arm may be integrally formed for convenient manufacturing and added structural strength. The fixture may include a cross bar for attaching to the junction box, with the cross bar serving to interconnect the junction box with the back plate. In one embodiment, the security lighting system provides an option of electrically interconnecting the system to a standard j-box or, alternatively, to an electrical conduit, as desired. In another embodiment, the cross-section of the back plate may have a different shape than the cross-section of the junction box.