The Flag of Ukraine (Ukrainian: Прапор України, romanized: Prapor Ukrainy) consists of equally sized horizontal bands of blue and yellow. As a national flag, the blue and yellow bicolour has been used since the 1848 Spring of Nations, when it was hoisted over Lviv Town Hall. It was officially adopted as a state flag for the first time in 1918 by the short-lived West Ukrainian People's Republic and subsequently used by the Ukrainian People's Republic, just before World War II it was also adopted by Carpatho-Ukraine in March 1939.

When Ukraine was part of the Soviet Union, the flag of the Ukrainian Soviet Socialist Republic was used and the bicolour flag was outlawed. The blue and yellow flag was provisionally adopted for official ceremonies in September 1991 following Ukrainian independence, before officially being restored on 28 January 1992 by the Parliament of Ukraine.

Ukraine has celebrated the Day of the National Flag on 23 August since 2004.