A thermoplastic resin composition and a molded article formed of the same. The thermoplastic resin composition includes: a polycarbonate resin; an aromatic vinyl copolymer resin; mica having an average particle diameter of about 200 μm to about 400 μm; a modified polyolefin; and a phosphorus flame retardant, wherein the modified polyolefin includes a first modified polyolefin including a repeat unit represented by Formula 1 and a repeat unit represented by Formula 2 as defined in the specification and a second modified polyolefin including the repeat unit represented by Formula 1 and a repeat unit represented by Formula 3 as also defined in the specification. The thermoplastic resin composition can have good properties in terms of rigidity, impact resistance, heat resistance, flame resistance, and balance therebetween.