Adolescence is a critical developmental period characterized by emotional, physical, and social changes that significantly impact self-esteem. This study investigated the influence of counseling in enhancing self-esteem among in-school adolescents in Ilorin metropolis, Kwara State, Nigeria. A descriptive survey research design was employed with 240 in-school adolescents selected through multistage sampling technique from both junior and senior secondary schools. Data were collected using a validated self-esteem questionnaire and analyzed using descriptive statistics (mean, standard deviation, percentages) and inferential statistics (t-test and ANOVA). The results revealed that counseling programs significantly enhanced adolescents' self-esteem by helping them believe in their abilities to fulfill goals (mean = 3.55), believe they deserve the best in life (mean = 3.48), and develop high academic standards without fear (mean = 3.42). No significant differences were found based on gender, religion, age, or school type, but a significant difference was observed based on class level (t = 2.00, p < 0.05). The findings underscore the importance of counseling interventions in secondary schools to promote positive self-esteem development among adolescents. The study recommends that school administrators should strengthen guidance and counseling programs, employ qualified counselors, and ensure regular counseling sessions for all students.