The performance of TiO2 nanoparticles is extremely attractive in various areas of chemical and biochemical engineering as they can effectively work by combining the photocatalytic property with various superior properties of the related nanostructure. The relevant photo-electrochemical detection has attracted considerable interest and shown potential applications in a wide range of areas. In this study, we have prepared new nanowhiskers of platinum-doped titanium dioxide (TiO2-Pt), which could be further used to fabricate a novel nanointerface for the sensitive detection of biomolecules including glutathione (GSH). Our observations demonstrate that the sensitive TiO2-Pt nanowhiskers biointerface could be readily fabricated by casting the TiO2-Pt nanowhiskers suspension on a glassy carbon electrode (GCE), which could readily combine the photocatalytic and eletrocatalytic properties of TiO2 nanocomposites to introduce a novel photoelectrocatalytic biosensor for GSH detection in real samples. Compared to other analysis strategies, the TiO2-Pt nanowhiskers-modified GCE showed a considerably high sensitivity for the detection of GSH due to the excellent photoelectrocatalytic ability of the porous TiO2-Pt nanowhiskers. Scanning electron microscopy (SEM), Raman spectroscopy, and electrochemical impedance spectroscopy have shown that Pt can readily blend with porous TiO2 nanowhiskers and facilitate the relevant catalysis property of TiO2, resulting in the enhanced photoelectrocatalytic effect. Thus, through the new strategy of the utilization of the excellent photoelectrocatalytic property of TiO2-Pt nanocomposites, it is possible to realize the rapid electrochemical detection of glutathione with high sensitivity, low cost, and good reproducibility.