ACYBER–PHYSICAL system (CPS) refers to the integrative system consisting of interconnected computing and control devices interacting with the physical infrastructure via sensors and actuators. Recently, there is a swift growth of CPSs ranging from smart grids to smart buildings, robotics, and other industrial control systems. They have formed the keystone of the sustainable growth of the economy, manufacturing, and smart and connected communities. Due to extensive applications of CPSs, their resilience, reliability, and security are paramount. Many factors, however, pose significant threats to CPSs and lead to high economic losses and social impacts. Software defects also make CPSs vulnerable to security attacks and coordinated cyber and physical attacks. To address this issue, emerging technologies and methods for understanding and improving the resilience, reliability, and security of CPSs are needed. This Special Section aims to provide a platform to help define, understand, and quantify the resilience, reliability, and security of CPSs. This Special Section received a great number of submissions of original research articles. Given the high quality of manuscripts we received, it was difficult and challenging to select the most relevant and novel works. After a rigorous review process, ten technical articles were selected, based on the significance and novelty of the research problem to the topic of the Special Section. These selected articles are grouped into three subtopics: 1) resilient consensus of CPSs; 2) advanced CPS control methods; and 3) diagnosis of CPS faults.