Objective: To determine the social factors associated with long-acting reversible contraceptives (LARCS) use among adolescent girls aged 17-19 years at Gatundu KMTC campus. Design: analytical cross-sectional. Settings: Kenya Medical Training College Gatundu Campus (KMTC). Population: 500 adolescent girls aged 17-19 years at Kenya Medical Training College Gatundu Campus. Main outcome measures: Age, marital status, home region, religion, culture, social influence and health care workers unfavourable attitudes effects LARCS use by the study participants. Method: Analytical cross-sectional study design. Materials: A sample of 238 subjects was randomly selected from a population of 500 adolescent girls aged 17-19 years at Gatundu KMTC and a semi-structured self-administered questionnaire was used to collect data. Quantitative data was analysed using descriptive and inferential statistics via statistical package for social sciences (SPSS) version 25. Chi square tests and Multivariate logistic regression analysis was conducted to assess factors associated with uptake of long-acting reversible contraceptives methods. Results: Majority (35.5%, n=84) of the subjects attributed LARCs non-use to religion, less than half 49% n=117 used LARCs without influence, (16.7%, n=40) did not use due to social influence,26.8% marital status and (34.2%, n=78) due to culture n=38). On cross-tabulation, marital status (p=0.002) and social influence (p= 0.029) were strongly associated with LARCs use.Conclusion: Inaccessibility and unavailability of LARCs to adolescents, as well as the perception of unfavourable attitudes among healthcare professionals, were the factors in the low use of LARCs. A multi-sectoral strategy on contraceptives should be deployed to increase the uptake of LARCs.