This study explores the ethical and legal challenges faced by nurses in caring for older adults with multimorbidities, focusing on issues related to patient autonomy, polypharmacy, and end-of-life care. Through semi-structured interviews with 15 nurses in Riyadh, Saudi Arabia, the research highlights the complexities of obtaining informed consent from patients with cognitive impairments and the ethical dilemmas of balancing autonomy and safety. The management of polypharmacy emerged as a significant concern, with nurses emphasizing the importance of thorough documentation and coordination among healthcare providers to prevent adverse drug interactions. End-of-life care and advance directives posed further challenges, particularly when family members disagreed with patients’ documented wishes. The study underscores the need for comprehensive strategies, including ongoing education, clear communication, and supportive institutional policies, to address these issues effectively. The findings suggest that enhancing nurses’ understanding of ethical principles and legal requirements is crucial for improving patient care and ensuring compliance with regulatory standards. Future research should aim to develop evidence-based guidelines to support nursing practice in managing these ethical and legal challenges.