Marriage timing is one of the important determinants of birth rates and health profile of both the mothers and infants. Child marriage is recognized as a major development issue that affects girls in many developing countries. The practice has been linked to several health risks, higher fertility, and lower education attainment. The aim of the current study was to estimate the prevalence and asses the determinants and effects of early marriage in Beni-Suef City. This was a cross sectional study was conducted from December 2019 to December 2020. Data were collected from 600 participants using a structured questionnaire. This study provide that the prevalence of early marriage was found to be 16.2% with 59.3% mothers residing in rural areas and 83% belonging to Muslim religion. Lower educational level (less than secondary school) and consanguinity were found to have significant association with early age of marriage. 41.2% of the mothers who married before the age of 18 years faced complications during delivery. 52.2% of the mothers married before the age of 18 years gave birth to low-birth-weight babies. Early age of marriage is an important public health challenge. Hence, a national multi-sectorial approach must be targeted to reduce this phenomenon.