We report a facile yet efficient strategy to synthesize biofunctionalized conjugated polyelectrolyte using click reaction between an amphiphilic oligopeptide (R10) and organic soluble polyfluorene (PF) as an example. PF-R10 shows the absorption and emission maxima at ~380 and ~430 nm in water, respectively. In addition, it exhibits enhanced fluorescence in acidic circumstance as compared to that in neutral environment because of reduced aggregation, which is confirmed by laser light scattering and atomic force microscopy studies. In view of the penetration property of the grafted R10 peptide, PF-R10 shows excellent cell uptake and labeling ability in cellular imaging.