Display omitted •New electrochlorination system for antibiofouling applied to marine optical sensors.•Platinum nanoparticles impregnated into fluorine tin oxide for chlorine generation.•High transparency, high catalytic properties, high stability and cost-effective anode.•Long-term antifouling performance with low consumption (100–350 µW/cm2). The concept of high electrocatalytic activity for chlorine generation has been pioneered through the development of a new system to prevent biofouling onto marine optical sensors surfaces. A combination of impregnated platinum (Pt) nanoparticles into the surface of fluorine tin oxide (FTO) was developed to create high optical transparent electrodes in glass substrates, with high catalytic properties, high durability, high stability and cost effectiveness, capable of generating sufficient biocide concentration (chlorine) with low electrical current. While chlorine generation, based on conventional electrodes with noble metal oxides, have been widely used for biofouling prevention, their difficulty of integration and their opacity makes them inappropriate for optical sensors protection. In the other hand, state-of-the-art FTO and ITO transparent films suffer from poor stability and durability in chlorine generation. This study highlights the effectiveness of creating simultaneous high optical transparent and high electrical conductivity electrodes, suitable for long-term electrochlorination and thus long-term monitoring in marine optoelectronic devices. Furthermore, their fabrication relies in an easy and low-cost process. The combination of specific Pt concentrations with FTO has been successfully proven for antifouling effect under seawater, exhibiting low consumption (100 – 350 µW/cm2), high catalytic activity with high binding stability of Pt nanoparticles against seawater properties. This new approach accelerates the search for high-performance antibiofouling strategies for marine optical sensors.