The Kansai region (関西地方, Kansai Chihō; [kaꜜɰ̃.sai, kaɰ̃.sai tɕiꜜ.hoː] ^ⓘ) or the Kinki region (近畿地方, Kinki Chihō; Japanese pronunciation: [kʲiꜜŋ.ki, kʲiŋ.ki̥ tɕiꜜ.hoː]) lies in the southern-central region of Japan's main island Honshū. The region includes the prefectures of Nara, Wakayama, Kyoto, Osaka, Hyōgo and Shiga, often also Mie, sometimes Fukui, Tokushima and Tottori. The metropolitan region of Osaka, Kobe and Kyoto (Keihanshin region) is the second-most populated in Japan after the Greater Tokyo Area.

The terms Kansai (関西), Kinki (近畿), and Kinai (畿内) have their roots during the Asuka period. When the old provinces of Japan were established, several provinces in the area around the then-capital Yamato Province were collectively named Kinai and Kinki, both roughly meaning "the neighbourhood of the capital".

Kansai (literally west of the tollgate) in its original usage refers to the land west of the Osaka Tollgate (逢坂関), the border between Yamashiro Province and Ōmi Province (present-day Kyoto and Shiga prefectures). During the Kamakura period, this border was redefined to include Ōmi and Iga Provinces. It is not until the Edo period that Kansai came to acquire its current form. (see Kamigata)

While the use of the terms "Kansai" and "Kinki" have changed over history, in most modern contexts the use of the two terms is interchangeable. The term "Kinai", once synonymous with Kinki, now refers to the Kyoto–Osaka–Kobe (Keihanshin) area at the center of the Kansai region. Like all regions of Japan, the Kansai region is not an administrative unit, but rather a cultural and historical one, which emerged much later during the Heian period after the expansion of Japan saw the development of the Kantō region to the east and the need to differentiate what was previously the center of Japan in Kansai emerged.

The name "Kinki" is pronounced similarly to the English word "kinky", which means "twisted" or "perverted". This has become a problem due to internationalization, and some organizations have changed their name as a result.

In April 2016, Kinki University (近畿大学, Kinki Daigaku) changed its English name to Kindai University. Keizai sangyō-kyoku (経済産業局, Kinki Bureau of Economy) uses "Kansai" in English notation, and Kinki Unyukyoku (近畿運輸局, Kinki Transport Bureau) also uses "Kansai" in English notation since 2015. The Kinki shōkō kaigi-sho rengō-kai (近畿商工会議所連合会, Kinki Chamber of Commerce and Industry Association) changed its name to "Kansai Chamber of Commerce and Industry Association" in July 2015.

In the fall of 2014, Kansai Keizai Rengōkai (公益社団法人関西経済連合会, Kansai Economic Federation) asked the government to unify the name of the local agency to "Kansai". In June 2003, the English name of the major private railway company Kintetsu Railway was changed from Kinki Nippon Railway Co., Ltd. to the official abbreviation Kintetsu Corporation. In April 2015, it was changed again to Kintetsu Railway Co., Ltd..

The Kansai region is a cultural center and the historical heart of Japan, with 11% of the nation's land area and 22,757,897 residents in 2010. The Osaka Plain with the cities of Osaka and Kyoto forms the core of the region. From there the Kansai area stretches west along the Seto Inland Sea towards Kobe and Himeji, and east encompassing Lake Biwa, Japan's largest freshwater lake. In the north, the region is bordered by the Sea of Japan, to the south by the Kii Peninsula and the Pacific Ocean, and to the east by the Ibuki Mountains and Ise Bay.