Zhanjiang is a port city in Southern China, located on the Leizhou Peninsula of the Guangdong province. The prefecture-level city of Zhanjiang administers the entire Leizhou Peninsula, directly opposite Haikou city, capital of Hainan province, across the Qiongzhou Strait. It is the southernmost port on the coast of mainland China and serves as a center of commerce and navigation for much of Southwestern China.

As of the 2020 census, the city's population stood at 6,981,236 (6,994,832 in 2010), of whom 1,931,455 resided in the built-up, urban center consisting of four urban districts: Chikan, Xiashan, Potou, and Mazhang. In 2007, the Chinese Cities Brand Value Report listed Zhanjiang among China's ten most liveable cities.

Under the rule of the Qin dynasty (221–206 BC), the area was part of the old administrative division of Xiang Shire. During the reign of the Han dynasty (206 BC-220 AD), the imperial government appointed Xuwen County as the administrative seat of the entire Leizhou Peninsula. The port of Zhanjiang was one of the earliest departure points on the Maritime Silk Road, its commerce spurring the growth of the urban center. During the Song dynasty (960 AD-1270 AD), a great number of Putian (Hinghwa) colonists settled in the area and would later become the ethnolinguistic majority in the Leizhou (Luichow) Peninsula. Large minority groups included the Baiyue, Cantonese, Tanka, and foreign merchants.

The region served as a small fishing port during its occupation by the French in 1898. The following year, the French forced the Chinese to lease a small enclave of Zhanjiang for 99 years as the concessionary port of Guangzhouwan, historically known in English as Kwangchowan or Kwangchow Wan. Much of the local population fled before the arrival of the French, so upon French invitation, Cantonese peasants from north of Leizhou came to repopulate the empty French possession, thus the local language became Yue Chinese. The French wanted to develop the port, which they called Fort Bayard, to serve as a logistical center for France's concessions in southern China, namely inland areas where France had exclusive rights to railway and mineral development. Their efforts, however, were hindered by the poverty and underdevelopment of the surrounding land. The French controlled the small enclave until 1943, when the Japanese invaded and occupied the area during World War II. At the end of the war, the enclave was briefly ceded to the French before being formally returned to China in 1946 by General Charles de Gaulle, then the French head of state.

Upon recovering the territory from the French, the Republic of China government decided to rename the area, which was historically under the jurisdiction of Zhanchuan county, with a Zhanchuan customs post on the eastern island of the territory. As "Zhanjiang" was a historical variant of "Zhanchuan", it was decided to name the city "Zhanjiang".

Following the establishment of the People's Republic of China in 1949, Zhanjiang developed new relevance. From 1957, Zhanjiang has developed into a major modern port serving Southern China, a deep-water harbor accessible to ships of up to 50,000 tons. In 1984, as part of the reform and opening up of China under Deng Xiaoping, Zhanjiang was designated as one of the "open" cities of China, where the central government invited foreign investment. This spurred the city's further industrial development, including the construction of shipyards and engineering works; automobile, electrical-appliance, and textile plants; as well as sugar refineries, flour and rice mills, and chemical works.

In the early 1990s, a new rail line was completed linking Zhanjiang with Guangzhou, the provincial capital. The line was later extended to Hai'an, at the southernmost tip of Leizhou Peninsula, where trains could be transported by the Guangdong–Hainan Ferry (part of the Guangdong–Hainan Railway) across the Hainan Strait to Haikou city.

Zhanjiang is to the southwest of the city of Guangzhou on an inlet of the South China Sea. It is on the eastern coast of the Leizhou Peninsula.