An aftertreatment system can include a radiation shield for reducing and/or redirecting radiative thermal energy. The aftertreatment system can include a first housing, a second housing, a first aftertreatment component, and the radiation shield. The first aftertreatment component is positioned within one of a first interior volume of the first housing or a second interior volume of the second housing. The radiation shield includes an attachment portion and a thermal barrier portion. The attachment portion is coupled to an exterior of the first housing or the second housing. The thermal barrier portion is structured to divert radiative thermal energy in a second direction different than a source direction of the radiative thermal energy.