Dongguan has experienced the most rapid urbanization since the Chinese reform and opening policy. To analyze the urban expansion in this city, in this study, 12 land use/land cover maps were produced using a multiple classifiers system on the Google Earth Engine platform. A long time-series land use dataset from 1987 to 2020, was achieved. The results indicate that, during the past 33 years, the urban area increased by 13.84 times and reached 1483.06 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in 2020, whereas cultivated land and forest continually decreased because of rapid urbanization. By analyzing the changes in urban forms and landscape indexes, Dongguan experienced a diffusion–coalescence–diffusion phase, and its urban expansion can be divided into three stages: The early-age urbanization stage (1987–1996), the rapid urbanization stage (1996–2011), and the intensive urbanization stage (2011–2020). The development of the economic and dual-level administration of Dongguan expanded the urban area surrounding the towns and traffic corridors, and, finally, formed a connected urban area. The urban expansion, just like sparking spots firing the prairie, is special and conforms to a Dongguan urbanization pattern.