We report the novel use of semiconductor photocatalysis for the deposition of metal onto insulating surfaces and the in-process formation of nano-structured porosity within this metal. In the process of Photocatalytically Initiated Electroless Deposition (PIED) we have developed a controllable, spatially selective and versatile metallisation technique with several advantages over traditional, non-photocatalytic techniques such as enhanced controllability and purity of the deposit as well as reduced operational costs and environmental impact. With the addition of a self-assembled, hexagonally close-packed microparticle template to the substrate prior to metal deposition, PIED can be used to fabricate thin metal films with highly ordered porosity on the nano-scale. Nanoporous metallisation in this way is able to produce substrates with potentially wide applications such as membrane and separation technology, energy storage and sensors – especially surface enhanced resonance Raman spectroscopy (SERRS).