The 4 volume set LNCS 17191-17194 constitutes the proceedings of the 24th International Confernce on Theory of Cryptography, TCC 2026, which took place in New York City, USA, during November 10-13, 2026. The 69 full papers included in the proceedings were carefully reviewed and selected from 177 submissions. They were organized in topical sections as follows: Part I: Secret Sharing and Correlated Randomness; MPC I; LPN and Code-Based Cryptography; Part II: MPC II; Pseudorandomness, Hashing, and Combiners; Foundations; Part III: Succinct Arguments I; Quantum Cryptography I; Succinct Arguments II; Part IV: Quantum Cryptography II; Zero Knowledge and Public Verifiability; Public Key Primitives; Homomorphic Encryption and Private Computation.