© 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.Worldwide, the COVID‐19 pandemic has resulted in significant changes in activity patterns and travel behavior. Some of these changes are due to responses to governmental or personal measures for controlling the spread of the pandemic (e.g. partial lockdowns, remote education, or work). This paper examines changes in human mobility over 1 year period (from March 1st, 2020 to March 30th, 2020) in Istanbul, Turkey, a megacity in developing countries. The study period imposed three distinct waves, 1st wave (March-April), the second wave (Nov/202–Jan/2021), and 3rd wave (March/2021-still continue). The paper includes two parts. The first part is an analytical analysis for traveler mobility trends using data of public transit automatic fare collection system and traffic volume counting sensors along with Istanbul metropolitan. For the 1st wave, mobility changes have a V-shape trend for public transit riders and a smooth U-shape for reported vehicles by highway sensors. Despite the severity level of the COVID-19 pandemic and mobility restriction measures during 2nd wave, there was a smooth drop in mobility indicating a change in human reaction toward pandemic severity. The second part is investigating differences in individuals’ trip characteristics for before the COVID-19 pandemic and after one year of pandemic based on data collected from an online survey. Tends to shift to use personal vehicle for daily trips, indicate more effective decisions should be implemented next to staggered working hours and reductions transit capacity to encourage travelers for using the sustainable transportation system.