With the development of networks and the rapid spread of mobile devices, individuals have been able to connect anywhere, anytime within the city, which evolves into a smart city. Emerging services and platforms in various fields such as housing, transportation, and energy continuously revitalize smart cities. This thesis examines the impact of the IT-enabled services utilized in smart cities on individual behaviors and the resulting societal effects. We focus on residential energy and shared transportation and empirically analyze how the introduction of the IT-enabled services changes the user behavior and affects society. The first essay demonstrates the impact of energy information systems installed within residential buildings on electricity consumption from the perspective of punitive nonlinear tariff system based on loss avoidance theory. Using monthly electricity consumption data in Korean apartment complexes, we find that electricity usage of households with energy information systems increases as temperature increases compared to households without the energy information systems. The second study investigates the impact of the entry of public bike-sharing service on local commercial districts in terms of transportation accessibility. Employing DID analysis with real-world local commercial district data and bike-sharing location and usage data, we find that more people visit the commercial districts after the installation of shared bike stations as it improves accessibility to commercial districts. The final essay analyzes the impact of the entry of car sharing service on urban traffic accidents. Leveraging real-world car sharing service data, we show that the overall incidence of traffic accident increases after the entry of car sharing as it improves vehicle accessibility for young drivers inexperienced in driving. In particular, the entry of car sharing affects accidents caused by novice or mid-experienced drivers or young drivers in their 20s and 30s are significantly affected by the entry of carsharing.