The surface fluorination of polypropylene (PP) was performed using F2 and O2 gas mixtures with different F2 gas proportions at 25 °C and 13.3 kPa for 1 h. The surface roughness of the fluorinated PP samples was approximately 1.5 times higher than that of the untreated sample (5 nm). The Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results showed that the PP-derived bonds (-C-C- and -CHx) decreased because they were converted into polar groups (-C–O, -CHF-, and -CFx), which increased the surface electronegativity of PP. The variation in the F2 gas proportion in the gas mixture significantly affected the hydrophilicity and surface composition of PP. At F2 gas proportions of <70%, the hydrophilicity of the fluorinated PP samples improved. Notably, the hydrophilic and negatively charged PP surface enhanced the dyeing of the polymer with basic methylene blue (MB). In contrast, at F2 gas proportions of >90%, the PP surface became hydrophobic owing to increased hydrophobic -CF3 bonds. Thus, enhanced PP dyeing can be controlled based on the composition of the F2 and O2 gas mixture.