A composite substrate for a rechargeable lithium battery, a method for manufacturing the same, and a rechargeable lithium battery including the same are provided. The composite substrate may include a support layer including a polymer, a first metal layer on a first surface of the support layer, and a second metal layer on a second surface of the support layer, where at least one selected from among the first metal layer and the second metal layer may include a plurality of crystal grains, and an average grain size of the plurality of crystal grains may be about 50 nm to about 200 nm.
