Aims and Objectives . To develop and test reliability and validity of the “factors affecting hypertensive treatment adherence” scale. Design . A sequential exploratory mixed method study was used. Methods . After item generation using a qualitative study and literature review, the psychometric properties of the scale were evaluated. Face, content, and construct validity, Cronbach’s alpha, and test‐retest reliability were used to validate the scales. Results . Data analysis showed that the scale had acceptable face and content validity. The scale had excellent stability (intraclass correlation = 0.89) and good acceptability of internal consistency ( α = 0.71). The exploratory factor analysis showed that the scale consisted of five subscales which were meaningful. Conclusion . Psychometric properties of the scale achieved the standard level, and it was sufficient to recommend for general use in future measures of caring in nursing.