Low-cost flexible thin-films exhibiting stimuli-responsive properties were fabricated on poly(methyl methacrylate) (PMMA) as the base supporting material. Labeling of this transparent thermoplastic with Congo red diazo dye revealed its simultaneous pH-responsive and temperature-responsive abilities. UV, FT-IR, and film stability studies identified the role of the dye and the polymer in the flexible thin-film stimuli-responsive behavior. This film is promising for future applications.