城市化（英语：Urbanization），又称城镇化、都市化，是指人口向城市聚集、城市规模扩大以及由此引起一系列经济社会变化的过程，其实质是经济结构、社会结构和空间结构的变迁。从经济结构变迁看，城市化过程是农业活动逐步向非农业活动转化和产业结构升级的过程；从社会结构变迁看，城市化是农村人口逐步转变为城镇人口以及城镇文化与生活方式和价值观念向农村扩散的过程；从空间结构变迁看，城市化是各种生产要素和产业活动向城镇地区聚集以及聚集后的再分散过程。在对城市化质量进行综合评价中，要考虑城市发展质量、城乡协调程度、城市化带来的文明成果以及为此付出社会、经济、环境等方面的代价。

Urbanization is a population shift from rural to urban areas, "the gradual increase in the proportion of people living in urban areas", and the ways in which each society adapts to the change. It is predominantly the process by which towns and cities are formed and become larger as more people begin living and working in central areas. The United Nations projected that half of the world's population would live in urban areas at the end of 2008. It is predicted that by 2050 about 64% of the developing world and 86% of the developed world will be urbanized. That is equivalent to approximately 3 billion urbanites by 2050, much of which will occur in Africa and Asia. Notably, the United Nations has also recently projected that nearly all global population growth from 2016 to 2030 will be absorbed by cities, about 1.1 billion new urbanites over the next 14 years.