Herein, we report antireflective structures on a highly flexible elastomeric lens membrane for tunable endoscopic imaging applications.The thin membrane increases light transmittance up to 96.8% in the visible region while enhancing the image contrast up to 56%, higher than that of a smooth membrane during lens deformation. This antireflective, tunable, liquid-filled lens offers new opportunities for compact endoscopic laparoscopy enabling maximum transmittance and variable zoom imaging in narrow and low-illumination environments.