Disclosed are a non-aqueous electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the non-aqueous electrolyte. The non-aqueous electrolyte for a rechargeable lithium battery includes a lithium salt; a non-aqueous organic solvent; and trialkylsilyl borate as an additive, wherein the non-aqueous organic solvent includes a solvent having a low melting point of less than or equal to about -50°C and a ionic conductivity of greater than or equal to about 6S/cm at 25°C.