This study investigated prevalence and patterns of online sexual grooming among female secondary school students in Oyo State, Nigeria. It adopted the descriptive survey design approach to collect data, using a multistage sampling procedure to select a total of 400 female secondary students from selected secondary schools, with 275 of the 400 administered copies of the questionnaires retrieved and analysed. The findings of this study revealed that between 60-80% of female secondary school students have experienced online sexual grooming, but much fewer (27%) have actually been actively involved in it.