Infant morbidity and mortality has been increasing due to inadequate exclusive breast feeding practice. These may be due to socio-demographic and personal factors affecting exclusive breastfeeding practice among women. The research assessed socio-demographic and personal factors affecting exclusive breastfeeding practice among women attending infant welfare clinic in Olabisi Onabanjo University Teaching Hospital in Sagamu, Ogun State. Descriptive research design was adopted. The populations were 200 women attending infant welfare clinic in Olabisi Onabanjo University Teaching Hospital obtained from four weeks clinic attendance record. Sample size was determined using total enumeration method and 170 respondents were included in the study. A researchers-developed questionnaire was adopted to collect data, validity of instrument was ascertained by experts in the field of study while reliability was determined using split half method and Cronbach alpha reliability coefficient was 0.8. Result revealed that more (45.6%) respondents had moderate knowledge level regarding exclusive breastfeeding practice. There is significant relationship between educational level, religion, occupation, knowledge level, ethnicity and exclusive breastfeeding practice (p= 0.000, p=0.000, p=0.001, p=0.000, p=0.003). Knowledge about exclusive breastfeeding practice among women is moderate. Educational level, religion, occupation, knowledge level and ethnicity affect exclusive breastfeeding practice. More awareness and health education should be done to improve exclusive breastfeeding practice.