With advances in aptamer selection technologies and nanomedicine, aptamer-functionalized nanoparticles are being explored as promising platforms for targeted therapeutic and diagnostic applications. In this Perspective, we outline recent progress in this field, as exemplified by Bamrungsap et al. in this issue of ACS Nano. Furthermore, we highlight the challenges and opportunities in translating current proof-of-concept designs into in vivo applications, with emphasis on the intrinsic properties of aptamers and their interplay with nanoparticles. With continuous efforts, we expect aptamer-functionalized nanoparticles to advance from preclinical into clinical development for further evaluation.