High-performance supercapacitors require the molecular-level linkage of charge transport components and charge-storage components. In this work, polypyrrole (PPy) was prepared via in situ chemical oxidative polymerization in the presence of a reactive dye (alizarin red S, ARS) which could play the role of both dopant and physical cross linker for pyrrole polymerization. The effects of ARS concentration on morphology, structure, electrical conductivity, and electrochemical performance were studied. When the feeding ratio of pyrrole: ARS was 2:1, the as-prepared ARS-doped PPy sample exhibited a high-mass-specific capacitance of 319 F/g at a current density of 1.0 A/g. All PPy-ARS electrodes possessed excellent capacitance retention. Especially, the specific capacitance of the sample with the highest ARS content increased by 18% of its initial value after 2000 cycles. The results demonstrated that the multifunctional dye ARS could effectively improve the performances of PPy as an electrode material for supercapacitors.