Zhenjiang got its current name at the time when Zhenjiang Prefecture was established in the Northern Song Dynasty in 1113, and this name remained unchanged in the Yuan, Ming and Qing dynasties. After the Revolution of 1911, Zhenjiang was renamed as Dantu County and then changed to Zhenjiang County in 1928. From 1929 to February 1949, Zhenjiang was the seat of Jiangsu provincial government (it moved to northern Jiangsu between 1937 and 1945 during the Japanese occupation). On April 23, 1949, Zhenjiang Prefecture, under the jurisdiction of Sunan Administrative Region, was divided into Zhenjiang City covering the urban and suburban areas, and Dantu County that surrounds the city. When Jiangsu Province was established by merging Sunan and Subei Administrative Regions in 1953, Zhenjiang Commissioner's Office was set up to administer Zhenjiang city and 10 neighbouring counties (Dantu, Danyang, Yangzhong, Jurong, Jiangning, Gaochun, Lishui, Wujin, Jintan and Liyang). Back then, Zhenjiang was both seats of Zhenjiang City and Zhenjiang Commissioner's Office (from September 1958 to September 1959, the Commissioner's Office was moved to Changzhou and renamed as Changzhou Commissioner's Office). In March 1983, Zhenjiang City was upgraded to a prefecture level city administering 4 counties and 2 districts. In 1987, 1994 and 1995, three counties of Danyang, Yangzhong and Jurong under its jurisdiction became sub cities respectively while Dantu County was turned into a district in 2002. Currently, Zhenjiang governs three county-level cities (Danyang, Jurong, and Yangzhong), administers three districts (Dantu, Jingkou, and Runzhou), and has two national-level development zones (Zhenjiang Economic and Technological Development Zone and Zhenjiang High-tech District).

By the end of 2024, Zhenjiang had comprised 56 towns and sub-districts, among which were 31 towns and 25 sub-districts.

At the end of 2024, the permanent population of the city was 3.228 million, an increase of 2,000 compared to the previous year. Among them, the urban population was 2,617,900, and the urbanization rate of the permanent population was 81.1%. Among the permanent population, the proportion of people aged 60 and above was 28.2%, an increase of 1.4 percentage points from the previous year. At the end of the year, the city's registered population was 2,640,100 people, including 1,297,500 males and 1,342,600 females.

Zhenjiang is one of the key cities in the province that highlights work on ethnic affairs. The city is home to 52 ethnic minorities such as Hui, Mongolia, Miao, Manchu, and Yi. The ethnic minority population is 29,118, accounting for 0.91% of the city's total. The top five ethnic minorities in terms of population are Hui, Miao, Tujia, Yi and Zhuang, accounting for 63% of the city's ethnic minority population.