Jiangsu Province is located in East China and occupies the southern part of the North China plains and the plains of the Lower Reaches of the Yangtze River. The name "Jiangsu" comes from the combination of the first Chinese character of "Jiang Ning" and "Su Zhou" (two prefectures in the Qing Dynasty); its short form is "Su". The provincial capital is Nanjing.

During the earliest Chinese dynasties, the area in what is now Jiangsu was far removed from the center of Chinese civilization, which was in the northwest Henan; it was home of the Huai Yi (淮夷), an ancient ethnic group. During the Zhou Dynasty more contact was made, and eventually the state of Wu (centered at Gusu, now Suzhou) appeared as a vassal to the Zhou Dynasty in south Jiangsu, one of the many hundreds of states that existed across northern and central China at that time. Near the end of the Spring and Autumn Period, Wu became a great power under King Helu of Wu, and was able to defeat in 484 BC the state of Qi, a major power in the north in modern-day Shandong province, and contest for the position of overlord over all states of China. The state of Wu was subjugated in 473 BC by the state of Yue, another state that had emerged to the south in modern-day Zhejiang province. Yue was in turn subjugated by the powerful state of Chu from the west in 333 BC. Eventually the state of Qin swept away all the other states, and established China as a unified nation in 221 BC.

Under the reign of the Han Dynasty (206 BC to 220 AD), which brought China to its first golden age, Jiangsu was a relative backwater, far removed from the centers of civilization in the North China Plain. Jiangsu was at that time administered under two zhou (provinces): Xuzhou Province in the north, and Yangzhou Province in the south. Although south Jiangsu was eventually the base for the kingdom of Wu (one of the Three Kingdoms from 222 to 280), it did not become significant role until the invasion of northern nomads during the Western Jin Dynasty, starting from the fourth century. As northern nomadic groups established kingdoms across the north, ethnic Han Chinese aristocracy fled southwards and set up a refugee Eastern Jin Dynasty in 317, in Jiankang (modern day Nanjing). From then until 581 (a period known as the Southern and Northern Dynasties), Nanjing in south Jiangsu was the base of four more ethnic Han Chinese dynasties facing off with northern barbarian (but increasingly sinicized) dynasties. In the meantime, north Jiangsu was a buffer of sorts between north and south; it initially started as a part of southern dynasties, but as northern dynasties gained more ground, it became part of northern dynasties.

In 581, unity was reestablished again, and under the Tang Dynasty (618 to 907) China once more went through a golden age, though Jiangsu at this point was still rather unremarkable among the different parts of China. It was during the Song Dynasty (960-1279), which saw the development of a wealthy mercantile class and emergent market economy in China, that south Jiangsu emerged as a center of trade

. From then onwards, south Jiangsu, especially major cities like Suzhou or Yangzhou, would be synonymous with opulence and luxury in China. Today south Jiangsu remains one of the richest parts of China, and Shanghai, arguably the wealthiest and most cosmopolitan of mainland China cities, is a direct extension of south Jiangsu culture.

The Jurchen Jin Dynasty gained control of North China in 1127, and the river Huai He, which used to cut through north Jiangsu to reach the Yellow Sea, was the border between the north, under the Jin, and the south, under the Southern Song Dynasty. The Mongols took control of China in the thirteenth century. The Ming Dynasty, which was established in 1368 after driving out the Mongols who had occupied China, initially put its capital in Nanjing. Following a coup by Zhu Di (later Yongle Emperor), however, the capital was moved to Beijing, far to the north. (The naming of the two cities continue to reflect this: "Nanjing" literally means "southern capital", "Beijing" literally means "northern capital.) The entirety of modern day Jiangsu as well as neighbouring Anhui province kept their special status, however, as territory-governed directly by the central government, and were called Nanzhili (南直隸 "Southern directly-governed"). Meanwhile, South Jiangsu continued to be an important center of trade in China; some historians see in the flourishing textiles industry at the time incipient industrialization and capitalism, a trend that was however aborted, several centuries before similar trends took hold in the West.

The Qing Dynasty changed this situation by establishing Nanzhili as Jiangnan province; in 1666 Jiangsu and Anhui were split apart as separate provinces, and Jiangsu was given borders approximately the same as today. With the start of the Western incursion into China in the 1840s, the rich and mercantile south Jiangsu was increasingly exposed to Western influence; Shanghai, originally an unremarkable little town of Jiangsu, quickly developed into a metropolis of trade, banking, and cosmopolitanism, and was split out later as an independent municipality. South Jiangsu also figures strongly in the Taiping Rebellion (1851 – 1864), a massive and deadly rebellion that attempted to set up a Christian theocracy in China; it started far to the south in Guangdong province, swept through much of South China, and by 1853 had established Nanjing as its capital, renamed as Tianjing (天京 "Heavenly Capital").

The Republic of China was established in 1912, and China was soon torn apart by warlords. Jiangsu changed hands several times, but in April 1927 Chiang Kai-Shek established a government at Nanjing; he was soon able to bring most of China under his control. This was however interrupted by the second Sino-Japanese War, which began full-scale in 1937; on December 13, 1937, Nanjing fell, and the combined atrocities of the occupying Japanese for the next 3 months would come to be known as the Nanjing Massacre. Nanjing was the seat of the collaborationist government of East China under Wang Jingwei, and Jiangsu remained under occupation until the end of the war in 1945.

After the war, Nanjing was once again the capital of the Republic of China, though now the Chinese Civil War had broken out between the Kuomintang government and Communist forces, based further north, mostly in Manchuria. The decisive Huaihai Campaign was fought in northern Jiangsu; it resulted in Kuomintang defeat, and the communists were soon able to cross the Yangtze River and take Nanjing. The Kuomintang fled southwards, and eventually ended up in Taipei, from which the Republic of China government continues to administer Taiwan and its neighbouring islands, though it also continues to claim (technically, at least) Nanjing as its rightful capital.

After communist takeover, Beijing was made capital of China and Nanjing was demoted to be the provincial capital of Jiangsu. The economic reforms of Deng Xiaoping initially focused on the south coast of China, in Guangdong province, which soon left Jiangsu behind; starting from the 1990s they were applied more evenly to the rest of China. Suzhou and Wuxi, two southern cities of Jiangsu in close proximity to neighbouring Shanghai Municipality, have since become particularly prosperous, being among the top 10 cities in China in gross domestic product and outstripping the provincial capital of Nanjing. The income disparity between north Jiangsu and south Jiangsu however remains large.