A method for metallizing through-glass vias in a glass substrate includes functionalizing a surface of the glass substrate with a silane. The glass substrate has an average thickness t and comprises a plurality of vias extending through the thickness t. The method further includes applying an electroless plating solution comprising a copper ion to deposit a copper seed layer on the functionalized surface, disposing an electrolyte within the plurality of vias, wherein the electrolyte comprises copper ions to be deposited on the copper seed layer within the plurality of vias; positioning an electrode within the electrolyte; and applying a current between the electrode and the glass substrate, thereby reducing the copper ions into copper within the plurality of vias such that each of the plurality of vias is filled with copper and the copper has a void volume fraction of less than 5%.