The two-volume proceedings set LNCS 13940 and 13941 constitutes the refereed proceedings of the 26th IACR International Conference on Practice and Theory of Public Key Cryptography, PKC 2023, which took place in March 2023 in Atlanta, GA, USA.The 49 papers included in these proceedings were carefully reviewed and selected from 183 submissions. They focus on all aspects of public-key cryptography, covering Post-Quantum Cryptography, Key Exchange and Messaging, Encryption, Homomorphic Cryptography and other topics.