Zhaodong (simplified Chinese: 肇东; traditional Chinese: 肇東; pinyin: Zhàodōng) is a city in southwestern Heilongjiang province, China. It is the southernmost county-level division of the prefecture-level city of Suihua, the center of which is located around 100 kilometres (62 mi) to the northeast and around 60 kilometres (37 mi) northwest of Harbin, the provincial capital. It forms part of the Harbin-Changchun Megalopolis.

Zhaodong lies near Songhua River to the south, being located in the central Songnen Plain.

As part of Suihua, human settlement began in the Paleolithic era. The Sushen people were the most prevalent, but the south and southwestern areas that now make up modern-day Zhaodong, Mingshui, Qinggang, and Anda were also settled by the Yemaek through the Western Zhou and Western Han dynasty. During the Sui and Tang dynasties, the Mohe people lived in the area of modern-day Zhaodong. During the Liao dynasty, Zhaodong was part of Liaoyang Prefecture.

In 1130, Emperor Taizong of Jin ordered the construction of Bali as a military town around 3 kilometres (1.9 mi) southwest of modern-day Sizhan Town. The Balicheng ruins [zh] have since been classed as one of the Major National Historical and Cultural Sites in Heilongjiang. Mongols settled in Zhaodong in the 13th century, during the Yuan dynasty, initially as part of Kaiyuan Circuit controlled by Khasar. In 1295, the Zhaozhou Tuntian Wanhu Fu was established, with Bali as its seat. It was administered as part of Tashan Guard under the Nurgan Regional Military Commission during the Ming dynasty. The Gorlos Mongols became the primary inhabitants in 1425 and remained until the late Qing dynasty.

In 1908, Zhaodong Sub-prefecture was created from Zhaozhou Sub-prefecture. Zhaodong became an administrative bureau [zh] in November 1912, then a county in July 1914. Between 1898 and 1940, the namegiving settlement, Zhaodong, now an administrative town under the city, was known as Mangou (满沟), after the Mongols of Rear Gorlos Banner (Zhaoyuan), who used the area at Zhaodong as grazing fields, the name being popularized from the historic railway station of the same name. It also developed the nickname Tiancaogang (甜草岗; lit. 'Sweet grass hill') for the wild growing liquorice in the hillside.

Zhaodong was formed as a second-class county of Suihua in 1929 by the Northeastern Political Affairs Committee [zh], following the abolishment of the circuit system. In July 1937, Zhaodong County government moved its headquarters from Changwu [zh] to Mangou, which prompted the name change in May 1940 to match the county. During the Chinese Civil War, Zhaodong was split off from Heilongjiang Province to become a directly administered county under Songjiang Province. With the establishment of the People's Republic of China in 1949, Zhaodong was returned to Heilongjiang.

In 1956, following the formation of Suihua Special District [zh], the counties of Zhaodong, Zhaozhou, and Zhaoyuan were the only subdivisions formerly under Suihua to remain under direct provincial control. Zhaodong came under jurisdiction of Harbin in August 1958, then Songhuajiang Prefecture [zh] in May 1960. Between June 1965 and December 1982, Zhaodong County returned to administration under Suihua via different offices and committees before Suihua was reduced in jurisdiction to a county-level city. Zhaodong became a county-level city in September 1986 and became administered by Suihua again in 2000, when the latter was made a prefecture-level city.

Grain production is widespread as a result of the fertile chernozem soil.