Background: Emergency Contraception (EC) is used after unprotected sexual intercourse, following sexual abuse, misuse of regular contraception or non-use of contraception. Seventeen percent of pregnancies in Kenya are unintended, potentially leading to unsafe abortion that contributes to the high maternal mortality rate in Country. According to 2016 Kenya Demographic and Health Survey (KDHS), the maternal mortality ratio was 362 maternal deaths per 100,000 live births. Female students in University or College are vulnerable to unplanned pregnancies and illegal abortions resulting in mortality, morbidity and psychosocial problems. Knowledge on EC is very important for students as they are not in stable relationships and not using regular contraception. Therefore, the aim of this study was to determine the knowledge and use of Emergency Contraception among female undergraduate students in the University of Nairobi. Materials and Methods: We used an institution-based cross sectional, quantitative study to sample was employed among 383 female undergraduate students at the University of Nairobi. The University of Nairobi has six colleges and systematic random sampling was used to select study participants from each college. Data were collected using self-administered questionnaires and analysed using SPSS Version 16. Bivariate analysis and logistic regression were used to determine sample characteristics significantly associated with knowledge and utilisation of Emergency Contraception. Results: Most (53%) of the respondents were sexually active, and only 20% of the sexually active female students had ever used Emergency Contraception. Emergency Contraception awareness was high at 86.4%. However, based on a predefined criterion, accurate knowledge of Emergency Contraception was low at 42.6%.The majority (82.5%) of the respondents depended on mass media as a source of information on Emergency Contraception. Factors associated with Emergency Contraception knowledge on bivariate analysis were: age 20 years and above (p =