A compact-miniaturized-flexible-single layer (CMFS) is proposed for the characteristic response of the band-stop and band-pass filter covering the bands of K and Ka frequencies. The FSS was designed using a modified square loop etched with rectangular and circular slots with a circular ring in the center. This proposed FSS is a symmetrical structure, which helps in achieving band-stop characteristics at 25 GHz with an insertion loss of −42.192 dB, which supports shielding applications, and band-pass filter characteristics at 32 GHz with a return loss of −34.64 dB. This filter characteristic supports millimeter-wave 5G communication in the K and Ka band range of frequencies. The designed structure is fabricated on the flexible Kapton substrate. The proposed CMFS-FSS is compact and miniaturized in size of 0.208λo × 0.208λo wavelength. Moreover, the overall thickness is 0.085 mm. The characteristics of the filter performance are simulated and measured on the normal surface and the curved surface to study the flexibility of the proposed design. The fabricated FSS identifies good performance between simulated and measured results. The design has achieved stable responses for both changes in polarization and was found stable up to 60° angle of incidence.