The national flag of Azerbaijan (Azerbaijani: Azərbaycan bayrağı), often referred to in Azerbaijani as Üçrəngli bayraq (English: Tricolour flag), is a horizontal tricolour that features three equally sized bars of bright blue, red, and green; a white crescent; and a centred eight-pointed star. The flag has become the predominant and most recognizable symbol of Azerbaijan. The bright blue represents Azerbaijan's Turkic heritage, the red represents progress, and the green represents Islam, which is Azerbaijan's majority religion.

The Azerbaijani Flag Day, held every year on 9 November, was established by Law No. 595 on 17 November 2009. The day commemorates the first official adoption of the tricolour as a national flag by the Azerbaijan Democratic Republic, which occurred on 9 November 1918. The flag was used by the republic until the 1920 Soviet invasion of Azerbaijan. It was reinstated, with slight variations to the colours and size, on 5 February 1991 following the country's independence from the Soviet Union.

The flag is referred to in the national constitution and mentioned twice in the national anthem, Azərbaycan marşı. On land, the flag is used as the civil, state and war flag; at sea, it is used as the civil, state, naval ensigns, and the naval jack. The Azerbaijani law regulates the flag's use and display, protecting it from desecration. The flag also has official status in Nakhchivan, an autonomous republic within Azerbaijan.