The articles in this special section examine emerging trends in Big Data for future smart cities. One of the greatest advantages in smart city is big-data- based decision making, which needs to capture, store, process, and analyze a large amount of data generated by several sources to transform the data into useful knowledge for making proper decisions. For example, with the help of big data and its Implementation, citizens could rapidly find available parking slots in large urban areas; big data can contribute in the city’s efforts to reduce pollution through the deployment of street sensors. These sensors can measure traffic flows at different times as well as total emissions. The government can implement actions to divert traffic to less congested areas in a move to reduce carbon emissions in a particular area.