Tianjin is a large city in northern coastal China. Administratively it is a municipality that has provincial-level status, reporting directly to the central government. Its urban area is the third largest in China, ranked only after Shanghai and Beijing.

Tianjin's urban area is located along the Hai He River. Its ports, some distance away, are located on Bohai Gulf in the Pacific Ocean. Tianjin was once home to foreign concessions in the late Qing Dynasty and early Republican era. The municipality now incorporates the coastal region of Tanggu, home to the Binhai New Area and the TEDA economic development zone. Tianjin Municipality borders Hebei province to the north, south, and west; the municipality of Beijing is to the northwest, and Bohai Gulf to the east.

Tianjin is at the northern end of the Grand Canal of China, which connects with the Huang He and Yangtze rivers.

Tianjin Municipality is generally flat, and swampy near the coast, but hilly in the far north, where the Yanshan Mountains pass through the tip of northern Tianjin. The highest point in Tianjin is Jiushanding Peak on the northern border with Hebei, at an altitude of 1078 m.

The Hai He River forms within Tianjin Municipality at the confluence of the Ziya River, Daqing River, Yongding River, North Grand Canal, and South Grand Canal; and enters the Pacific Ocean at Tianjin Municipality as well, in Dagu District. Major reservoirs include the Beidagang Reservoir in the extreme south (in Dagang District) and the Yuqiao Reservoir in the extreme north (in Ji County).

The urban area of Tianjin is found in the south-central part of the Municipality. In addition to the main urban area of Tianjin proper, the coast along the Bohai is lined with a series of port towns, including Tanggu and Hangu.

Tianjin's climate is a monsoon-influenced humid continental climate (Koppen climate classification Dwa) characterized by hot, humid summers, due to the monsoon, and dry, cold winters, due to the Siberian anticyclone. Average highs in January and July are 2 °C (36 °F) and 31 °C (87 °F) respectively). Spring is windy but dry, and most of the precipitation takes place in July and August. Tianjin also experiences occasional spring sandstorms which blow in from the Gobi Desert and may last for several days.