Background/Objectives: Implementing a person-centered practice is considered a priority in healthcare, and the development of a solid and positive therapeutic relationship is a fundamental element. This study conducted a cross-cultural adaptation of the Person-Centered Therapeutic Relationship in Physiotherapy Scale to European Portuguese and contributed to its validation through the study of its structural validity and internal consistency. Methods: This study was conducted from October 2021 to July 2023 and included two phases: a methodological study of cross-cultural adaptation (phase 1) and a transversal study to assess the psychometric properties (phase 2). Structural validity was analyzed using exploratory factor analysis and internal consistency was estimated using Cronbach’s alpha (α). A p-value < 0.05 was considered to indicate statistical significance. Results: The Person-Centered Therapeutic Relationship in Physiotherapy Scale was successfully culturally adapted to European Portuguese (phase 1). During phase 2, 203 individuals [mean age: 50.16 ± 13.10 years (range 18–80 years)] with musculoskeletal conditions, mostly female (63.1%), were recruited. The factorial solution explained 74.7% of the total variability and retained three factors, grouping items 9 to 15 in a common factor (professional empowerment and therapeutic communication). Adequate internal consistency was found (Cronbach’s α = 0.889). Conclusions: This study culturally adapted an instrument to European Portuguese, which allows the assessment of the person-centered therapeutic relationship in physiotherapy, presenting adequate internal consistency. Future studies should contribute to the remaining validation of the instrument so that it can be available to the Portuguese population.