Visible-light-responsive photocatalysts can directly harvest energy from solar light, offering a desirable way to solve energy and environment issues. Here, we show that one-dimensional poly(diphenylbutadiyne) nanostructures have high photocatalytic activity under visible light without the assistance of sacrificial reagents or precious metal co-catalysts. Transmission electron microscopy and nanoscale infrared characterizations show that polymer nanostructures remain unchanged after many photocatalytic cycles. Our findings may aid in the development of semiconducting-based polymers for applications in self-cleaning surfaces, hydrogen generation and photovoltaics.