This is the 24th edition of the International Conference on Practice and Theory of Public-Key Cryptography (PKC), the main annual conference with an explicit focus on public-key cryptography, sponsored by IACR, the International Association for Cryptologic Research. Original research papers on all aspects of public-key cryptography, covering theory, implementations and applications, are solicited for submission to PKC 2021. Given NIST's efforts on standardization of post-quantum cryptography (PQC), this year PQC constructions and cryptanalysis will receive special attention.