vertically striped red-blue-red national flag with a group of yellow symbols on its hoist stripe. The flag's width-to-length ratio is 1 to 2.

Historically, blue has been associated with the Mongolian (Mongolia) people as a symbol of the open skies under which they traveled throughout Central Asia. Mongolia also has frequently utilized yellow in its flags, as a symbol of the Dge-lugs-pa (Yellow Hat Sect of Tibetan Buddhism), which was popularized there in the 16th century. In 1911, when the modern Mongolian state was first established, its yellow flag bore in the centre in blue a traditional emblem known as the soyonbo. This consists of figures (flame, sun, moon, yin-yang, triangles, and bars) representing philosophical principles inherent in Mongolian culture and religion. Below the soyonbo was a lotus blossom, symbol of purity.

In 1921 a communist government came to power and introduced the Red Banner, but the 1911 flag was restored in 1924. During World War II, Mongolia adopted a flag (1940–45) resembling those of member states in the Soviet Union (Union of Soviet Socialist Republics), which it seemed Mongolia was likely to join. In 1945, however, the soyonbo of the 1924–40 flag was shifted toward the hoist and represented in yellow for greater visibility; the lotus was removed and, above the soyonbo, the usual communist star was added. The red background was replaced by equal bars of red-blue-red, symbolizing communism and Mongol nationalism. This flag continued in use after the overthrow of the communist regime until February 12, 1992. The only change made in the flag at that time was the removal of the yellow five-pointed star, which no longer reflected political realities.