A thermoplastic resin composition includes: a polyester resin; a white pigment; a core-shell structured impact modifier; and a modified polyolefin resin. Exemplary compositions include polycyclohexylenedimethylene terephthalate (PCT) resin; titanium oxide; a core-shell structured impact modifier obtained by grafting methyl (meth)acrylate to the polydimethylsiloxane rubber core; and an ethylene-methacrylate copolymer. The thermoplastic resin composition is usable for the production of molded article as a reflector or reflector cup for a LED (light-emitting diode) that maintains reflectance at elevated temperature.