Urbanization is a complex system that has led to severe air pollution. There is a growing interest in exploring the relationship between urbanization and atmospheric pollutants at multiple scales. The impact of urbanization on particulate matter having a diameter <2.5 μm (PM_2.5) has been investigated by researchers worldwide, while some attention has been paid to the impact of urbanization on nitrogen dioxide (NO₂) concentrations. A majority of the countries in the Belt and Road (B&R) region are currently in the stage of rapid urbanization and are suffering from NO₂ pollution. However, the focus on the spatiotemporal variation and driving factors of NO₂ concentrations in the B&R region is almost lacking. To fill this gap, in this study, we explored the spatiotemporal variation in the tropospheric NO₂ vertical column density as a representative of the NO₂ concentrations in the 74 countries of the B&R region, and further investigated the impacts of different dimensions of urbanization on the NO₂ concentrations. The results indicated that the annual mean NO₂ concentrations in the B&R region were fluctuating during 2005 and 2015; with low concentrations in high or low latitude regions, and high concentrations in middle latitude regions. The spatial dependence of NO₂ was statistically significant in the B&R region. The NO₂ concentrations in developed countries, especially in Western Europe, exhibited a significant downward trend. Distinct trends can be observed for the NO₂ concentrations of developing countries: China has reduced its NO₂ concentrations after reaching a peak in 2011; the NO₂ concentrations have decreased slowly in Malaysia and Indonesia, while it has increased steadily in India, Russia, and certain Western Asian countries. Both population urbanization and land urbanization in the B&R region continued to increase, with high levels in the southwest and low levels in the northeast. Land urbanization had a much stronger influence on air quality than population urbanization. The gross domestic product (GDP), car ownership, and land urbanization had a significant positive effect on the NO₂ concentrations, whereas the forest cover rate had a negative effect on the NO₂ concentrations. Our study suggested that changing the modes of economic growth, limiting the increase in vehicle ownership and built-up land, and establishing a coordinated management system of air pollution control among the B&R nations were key measures for the construction of a green B&R region. Further, intensive urban land use and sustainable management of forest and urban green area were expected to remarkably support the achievement of air pollution control and climate change mitigation simultaneously. Moreover, adopting new clean technologies and higher environmental standards would be highly required. For instance, more funds should be invested for research on fuel savings, emission reduction technologies of fuel vehicles, and new energy vehicles. These findings could facilitate the understanding of the dynamics and driving forces of the NO₂ concentrations, laying a basis for achieving a green transformation of regional and national economies in the pursuit of 2030 Agenda for Sustainable Development.