The aging trend in the population, the high rate of hospitalization, the affliction by multiple chronic illnesses, and the increased vulnerability of older people when hospitalized undoubtedly require a person-centered approach to healthcare—an approach that values a person’s participation in the healthcare relationship, supports shared decision making and mutual understanding, and respects a person’s values, preferences, and beliefs. However, despite widespread recognition that the adoption of such a clinical practice paradigm is paramount, its implementation and development are still challenging for various health systems and professionals worldwide. The implementation strategy for such a healthcare paradigm must be based on each country’s health system organization and practice contexts, as well as the professionals involved. The present work aims to provide guidelines for the understanding of the state of development of person-centered practice in the daily care of hospitalized older adults with chronic illnesses within the internal medicine department of a secondary hospital in an urban area of Portugal. We focus on the characterization of (i) the perceptions of a multidisciplinary team working at an inpatient hospital department of person-centered practice, (ii) the perceptions of hospitalized older adults with chronic illnesses about person-centered practice, (iii) the work culture of an inpatient hospital department with a high prevalence of older adults with chronic illnesses, (iv) the Person-Centred Practice Framework at the organizational and structural levels of the healthcare system, and (v) the elements that influence the implementation of person-centered practice at the individual, organizational, and structural levels in this specific hospital context. To this end, a mixed-methods analysis with a convergent design was planned to use questionnaire instruments to collect data in parallel and independently from distinct samples of health professionals and older inpatient adults within this department. Furthermore, health policies and strategic plans will be analyzed to identify and evaluate references and guidelines for the practice of person-centered care. Studying the dimensions of clinical practice in this specific healthcare context following the Person-Centred Practice Framework can allow us to understand the extent of its development in terms of prerequisites, care environment, care processes, and the macro-context of the healthcare system. Therefore, it is possible to identify and characterize the dimensions achieved and those that need to be improved and, thus, establish a starting point for the definition of new strategies to advance practice towards person-centeredness and monitor changes in healthcare practice.