The purpose of the current study was to explore the personal and environment factors that influence career maturity of senior secondary students from low-income family environment. The main objective of the study was to determine whether personal factors including age, gender, self-concept, and environment factors such as socio-economic status, parental support and parents` level of education would significantly predict career maturity of senior secondary students from low-income environment. Furthermore, the study also examined the mediating role of career self-efficacy (CDMSEF) between parental support, self-concept and career maturity. Attaining Career Maturity is very vital for secondary school students because career choice made at this stage can have ever-lasting impact on an individual’s life. The study used quantitative survey method and collected data using survey questionnaires. The population for this study was all senior secondary students (form three and four) from Wajir County, Kenya. Simple random sampling was used to select respondents. A total of 525 senior students from five secondary schools completed the survey. The major analytical tools and procedure used were Multiple Regression Analysis and full-fledge SEM modeling. MRA analyses indicates father`s education level of the environmental factors accounting for significance variance of career maturity. Furthermore, all measurement models reported adequate goodness of fit. The Full-fledge SEM analysis on the proposed model reported fair fit indices with self-concept predicting strongly career maturity. Findings indicate mediating role of career self-efficacy. The study indicates that students’ career prospect and their knowledge about different occupations was minimal.