This 2-volume set constitutes the post-conference proceedings of the 4th EAI International Conference on Cognitive Computing and Cyber Physical Systems, IC4S 2023, Bhimavaram, Andhra Pradesh, India, during August 4-6, 2023. The theme of IC4S 2023 was: cognitive approaches with machine learning and advanced communications. The 70 full papers were carefully reviewed and selected from 165 submissions. The papers are clustered in thematical issues as follows: machine learning and its applications; cyber security and signal processing; image processing; smart power systems; smart city eco-system and communications.