Clinical reasoning is a vital competence for nursing students, as it is required for solving problems arising in complex clinical situations. Identifying the factors that influence nursing students’ clinical reasoning competence in the social context can help their implicit educational needs. Therefore, this study aimed to determine the factors associated with developing clinical reasoning competency among undergraduate nursing students. In total, 206 senior nursing students were included in this study. Self-reported measures were used to obtain data on participants’ clinical reasoning competence, problem-solving abilities, academic self-efficacy, and level of clinical practicum stress. Relationships among continuous variables were analyzed using Pearson’s correlation coefficients. A multiple linear regression analysis was conducted to identify factors related to clinical reasoning competence. Our findings show that participants with better problem-solving abilities and academic self-efficacy perceived themselves as having higher levels of clinical reasoning competence. Nursing students with lower clinical practicum stress reported higher clinical reasoning competence. Significant factors identified were younger age and subcategories of problem-solving ability such as problem clarification, alternative solution development, planning/implementation, and self-regulated efficacy. Our findings highlight essential factors necessary for developing a nursing curriculum that contributes to professional nurses’ clinical reasoning competence.