We describe the synthesis and self-assembly of amphiphilic semiconducting polymers composed of a polythiophene derivative (i.e., poly[3-(2,5,8,11-tetraoxatridecanyI)thiophene] (PTOTT)) and an oligonucleotide, DNA-b-PTOTT. These new bioconjugated polymers combine the excellent optoelectronic properties of semiconducting poly-PTOTT-b-DNA mers and the programmable molecular recognition properties of DNA. Because of the unique combination of rigid polythiophene and highly negatively charged DNA, they self-assemble into size-controllable vesicles in water. DNA-modified one-dimensional polythiophene nanoribbons were formed by simultaneous assembly of DNA-b-PTOTT with PEG-b-PTOTT, demonstrating that various types of DNA-modified functional nanostructures can be formed by the mixed assembly. This approach offers a new pathway to couple various types of soft optoelectronic nanostructures with DNA's molecular recognition properties.