Despite high sexual activity among adolescent girls in Kenya, contraceptive uptake is very low with only about 26 percent sexually active adolescent girls currently using a contraceptive method. This exposes them to HIV infections and unplanned pregnancies which consequently lead to school dropouts, unsafe abortions, and lack of employment opportunities. This cross-sectional study aimed at assessing the utilization of contraceptives among secondary school adolescent girls in Karuri Town Council, Kiambu County. Overall, 421 girls aged between 13.0 to 19.0 years took part in the study. Findings showed that despite majority (77.5%) of the adolescent girls having had sexual debut by the age of 15 years, contraceptive utilization was very low at 43%. The results revealed that age of the adolescent, knowledge of contraceptives options, perception and accessibility of the contraceptives had positive significant effect on contraceptive utilization.