In this work, the response of peeled-off Gafchromic EBT2 film to argon plasma jet (APJ) was investigated. Peeled-off Gafchromic EBT2 films were exposed to APJ for different durations of varying steps from 0 to 70 s at ambient conditions. Thereafter, the films were scanned with a flatbed scanner of high spatial resolution and color depth of 16 bits per color channel. The optical properties were measured using a UV-Vis spectrophotometer. The induced chemical modification in the active layer was confirmed by ATR-FTIR spectroscopy. The pixel values correlation of each color channel of peeled-off Gafchromic EBT2 film and the exposure time by APJ at different durations were studied. The obtained results showed that the pixel values of the red and green color channels of the peeled-off Gafchromic EBT2 film exponentially decrease with increasing the exposure time to APJ, with decay constants of 0.010 ± 0.024 and 0.071 ± 0.011 for the red and green channels, respectively. The blue channel exhibits poor and anomalous responses compared to both red and green color channels. The two characteristic peaks in the UV-Vis absorption spectra at the wavelengths of 580 ± 4 nm and 632 ± 4 nm for the peeled-off Gafchromic EBT2 film go up exponentially as the exposure time increases. The ATR-FTIR spectra contain two characteristic new C = C bonds; the first is formed due to a solid-state 1,4-polymerization reaction as conjugated with neighboring C ≡ C, while the second is further stabilized by conjugation to allene structure, increasing the double bond character, while the latter is the major contributor. The obtained results of the peeled-off Gafchromic EBT2 film can be utilized in APJ diagnosis and measurements.