Purpose:This study aims to assess nurses’ knowledge and attitude towards pain assessment and management as an essential component of holistic nursing and patient care. Study Design: A cross-sectional descriptive design. Methods: A convenient sample of 282 nurses working in four health care institutions in the South region of Saudi Arabia was enrolled. The Knowledge and Attitudes Survey Regarding Pain tool was used to collect data from April-July 2021 through a web-based survey. Findings: The knowledge level and attitude of the nurses toward pain assessment and management was inadequate. The participants’ correct mean score was (2.98). Forty percent achieved a passing score of 70%. Female nurses, postgraduate, working in medical-surgical units, had 5 to 10 years of work experience had higher knowledge and attitude levels. The barriers were categorized as patients, nurses, physicians, and system-related barriers. The most perceived barriers were nurses’ shortage (76.2%); restricted opioids regulations (66.7%); and unavailable comfort measures as alternatives (59.9%). Conclusions: Inadequate nurses’ knowledge and negative attitudes toward pain assessment and management is an alarming global concern. Healthcare administrators have to improve nurses’ competencies through continuous education and training programs, adopt updated guidelines and eliminate barriers to achieve holistic patients’ care including optimal pain control.