An optimized approach is applied to realize the transfer printing of an In0.2Ga0.8As/GaAs/In0.2Ga0.8As trilayer nanomembrane (NM) onto a plastic substrate with high quality. Bendable metal-oxide-semiconductor capacitors (MOSCAPs) are fabricated on the transferred NM. A detailed COMSOL simulation study is conducted to investigate the mechanical bending behavior induced tri-principle stress of the NM on flexible substrates. The electrical characteristics of the fabricated MOSCAPs exhibit almost no hysteresis voltage of only 0.03 V, an extremely low gate leakage of 10-6 to 10-7 A/cm2, and low accumulation frequency dispersion, thus indicating the possibility of achieving high performance III-V MOS transistor operation. The impact of mechanical strains on the flatband voltages has been carefully investigated from the capacitance-voltage (C-V) measurements. The corresponding accumulation capacitance shows good robustness under tensile bending conditions. The results indicate an important step toward the realization of mechanically flexible high-performance III-V MOS field-effect transistors and provide understanding of mechanical effects on the behavior of such devices.