Adolescent pre-martial sexual activities often come with sexual health problems such as HIV/AIDS and pregnancies not planned for. While society contends with this social problem, the forces of globalization through the internet offer a wide range of sexuality related information, some of which expose adolescents to risk-bearing practices. Earlier works on adolescent sexuality in Nigeria have drawn attention to the roles of family socio- economic background, peer influence, prolongation of adolescence resulting from longer years of schooling, and a number of other factors in shaping adolescent sexuality. The role of online sexual activities, a rather recent phenomenon, in shaping adolescent sexuality in Nigeria remains, however, an area yet to be addressed by researchers. This work set out, therefore, to examine the effect of general online exposure to sexuality related information and involvement in online sexual activities on real life sexual practices among adolescents in metropolitan Lagos using a combination of quantitative and qualitative research methods.