巴库（阿塞拜疆语：Bakı; 英语：Baku）是阿塞拜疆的首都、经济文化中心。巴库同时也是里海最大港口，外高加索最大城市。面积2192平方公里，人口300万（2008年计算）。巴库全市分为内城和新城两部分（亦有将苏联时期兴建区域分别划分的）。

在2007年，伊斯兰会议组织文化部长宣布巴库为2009年伊斯兰文化中心。为2015年第一届欧洲运动会主办国。巴库曾先后申办2016年夏季奥运会和2020年夏季奥运会，但皆因基础设施不完备没有入围。不过由于阿塞拜疆歌手艾尔与妮基在2011年欧洲歌唱大赛获得冠军，终使巴库获得举办2012年欧洲歌唱大赛的机会。

Baku (Azerbaijani:Bakı, IPA: [bɑˈcɯ]) is the capital and largest city of Azerbaijan, as well as the largest city on the Caspian Sea and of the Caucasus region. Baku is located 28 metres (92 ft) below sea level, which makes it the lowest lying national capital in the world and also the largest city in the world located below sea level. It is located on the southern shore of the Absheron Peninsula, alongside the Bay of Baku. At the beginning of 2009, Baku's urban population was estimated at just over two million people. Officially, about 25 percent of all inhabitants of the country live in Baku's metropolitan area.