The aim of this study was to determine the impact of social media on the practice of modern journalism in Nigeria with a focus on journalists in Lagos metropolis. As the inception of information communication technology such as the internet has made it possible to find out about events without actually being there. Journalists can report news across the world over the internet. Throughout history, developments in technology and communication have gone hand-in-hand, and the latest technological developments such as the internet have resulted in the advancement of the science of communication to a new level. The process of human communication has evolved over the years, with many path-breaking inventions and discoveries heralding revolutions. The invention of pictographs or the first written communication in the ancient world brought about written communication. These writings were on stone, and remained immobile. To achieve this aim, a critical review to related literature was made. Relevant theory which was used to gratify the study was the social responsibility theory. Quantitative research design was used in which cross-sectional survey method was adopted while the data collection instrument was questionnaire. chi-square were used. Subjects were drawn from journalists in Lagos metropolis in Lagos State, using the purposive sampling technique. Three research questions and one alternative hypothesis guided the study. Research findings showed that social media have enhanced the productivity of journalists in Lagos state and a great number of journalists use them to source for news among other things. To this end, the researcher recommended that journalists should carry out a research on the available social media tools in order to identify reliable and trustworthy social networking sites and use them to discharge their journalistic duties. The researcher suggested that further studies should be carried out on the role of social media in sustaining democracy, advertising, public relations and public opinion polls.