The aim of this study was to determine the impact of social media on modern journalism practices in Nigerian with a focus on journalists within 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, development in technology and communication have gone hand-in-hand, and the latest technological development 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 revolution. Relevant theories which were used to gratify the study. Social Responsibility Theory and Technological Determinism Theory. Quantitative research design was used in which cross-sectional survey method was adopted while the data collection instrument was questionnaire. Subjects were drawn from journalists in Lagos metropolis in Lagos State, using the purposive sampling technique. Three research questions to guided the study were used. 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.