An electrolyte for a rechargeable lithium battery comprising a lithium salt, an organic solvent and an additive, where the additive includes a sulfur-containing compound represented by Chemical Formula 1, a phosphazene compound represented by Chemical Formula 2, and a nitrile-based compound. A rechargeable lithium battery comprising the electrolyte. In Chemical Formulae 1 and 2, each substituent is the same as defined in the detailed description.