Social media use, and Facebook involvement in particular, has become embedded in the daily routines of young adults, with measurable implications for their psychological well being and self perception. This study examined the role of social media Facebook on the self concept of young adults at the University of Buea, South West Region of Cameroon, operationalising self concept through three sub constructs self esteem, self image, and the ideal self. Facebook engagement was framed in terms of motivation, uses and gratifications, and social comparison. The study was grounded in three theoretical lenses, namely symbolic interactionism, social comparison theory, and self objectification theory. A quantitative cross sectional survey design was adopted. A structured, closed ended questionnaire was administered to 450 active Facebook users drawn through random sampling from three faculties of the University of Buea. Data were captured in EpiData version 3.1 and analysed in SPSS using descriptive statistics, the chi square test, and the non parametric Spearman rho correlation, with significance set at the 0.05 level. Descriptive results showed that Facebook involvement affected self esteem 83.2 , self image 79.0 , and the ideal self 77.2 of respondents. Inferential results confirmed a statistically significant negative relationship between Facebook use and each dimension of the self concept self esteem rho = .211, p = .001 , self image rho = .237, p .001 , and ideal self rho = .245, p .001 , with an overall self concept effect of rho = .250 p .001 . Female respondents, younger users 18 to 25 years , and those whose principal motivation was posting and commenting on pictures were consistently more affected. The study recommends targeted sensitisation on the content shared on Facebook, a stronger and exemplary presence of conventional media on social platforms, the introduction of social media as a formal course in universities, and balanced regulation of social media use. social media, Facebook, self concept, self esteem, self image, ideal self, social comparison, young adults, Cameroon. 66-79 Issue-4 Volume-10 Michael Kengnjoh