PtO decorated multi-walled carbon nanotubes (MWCNTs) were prepared by a polymer ligand assisted strategy and applied as the counter electrode (CE) in dye-sensitized solar cells (DSCs) for the first time. Compared with the energy conversion efficiency (E_ff) of Pt CE based DSCs, the DSCs with PtO–MWCNTs CE showed an overall E_ff of 8.67%, giving an improvement of 12.7%. Better electrocatalytic activity towards I₃⁻/I⁻ redox pairs than Pt CE indicated that the PtO–MWCNTs was a promising electrocatalyst for DSCs.