Herein, we designed alkylated lysine-dendron oxytocin amphiphiles (ALOAs) 1G-OTK and 2G-OTK, which were self-assembled into spherical nanoparticles and nanostrips, respectively, and showed superior stability compared to native oxytocin. We found similar trends in the functional activity of ALOAs and native OT for human oxytocin receptor. This work may inspire the development of peptide drugs for clinical applications.