A modular sensor system includes a receptacle that is configured to be coupled to a luminaire. Further, the modular sensor system includes a sensor housing that is configured house a sensor device therein. The sensor housing includes flexible snap fit features that are configured to removably couple the sensor housing to the receptacle by a twist and lock mechanism. Each flexible snap fit feature includes a curved cantilever snap fit defined by a portion of the sidewall of the sensor housing and a hook that extends radially outward from the curved cantilever snap fit. The hooks are configured to engage corresponding slots in the receptacle to couple the sensor housing to the receptacle by rotating the sensor housing within the receptacle in a first direction. The hooks are also configured to decouple the sensor housing from the receptacle by further rotating the sensor housing in the first direction.