Parents play a significant role in shaping their children’s career choices. However, in Murang’a County, Kenya, there is a lack of research focusing on the specific aspects of parental support, and science self-efficacy, interacting with students’ career decisions. Furthermore, there is a limited understanding of how parental factors, in conjunction with students’ self-efficacy in science subjects, influence the career choices students ultimately make. This research aims to fill this gap by examining how parental career support and students’ self-efficacy in science interact to influence career decision-making among students attending public secondary schools. The study was grounded in the Social Cognitive Career Theory, which prompted the following research inquiries; are there interrelationships between parents’ support, students’ self-efficacy for science, and students’ career decision making. The study involved a sample of 482 students in the third year of public secondary schools. The sample size was determined using Cochran’s formula. The selection of 11 schools, including both single-gender and mixed schools, was based on purposive sampling and proportionate stratified random sampling methods. Participants within these schools were chosen through random sampling. The data were gathered and analyzed using SPSS software. To test the hypotheses, statistical techniques such as Pearson’s product moment correlation coefficient, analysis of variance, and multiple regression were employed. The study observed parents’ support, self-efficacy in science, and career decision making were interrelated. Recommendations on the inclusion of specific parental attributes in enhancing science self-efficacy to improve students’ choices in sciences were made.