This paper discusses the influence of social media on the academic performance of boys in secondary schools in Bungoma East and Webuye West Sub Counties, Kenya. The period 2011-2014 had shown the performance of secondary school boys in these study area to be lower than that of girls. Purposive sampling was used to select boys’ secondary schools in Bungoma East and Webuye West sub-counties while random sampling was used to get a sample of respondents from the boy’s schools. The study was informed by the social development theory by Lev Vygotsky. Primary data collection was done by use of questionnaires while document analysis was used to collect secondary data especially on the performance of students in the mid-year exams, 2016. The study used multiple linear regression to analyze the data; findings of which were presented in tables. The study results showed that social media has a significant influence on the academic performance of secondary school boys in Bungoma East and Webuye West Sub Counties. This paper thus concludes that secondary school boys’ exposure to social media in is high and, consequently, negatively affects their academic performance.