The flag of Yemen (Arabic: علم اليمن‎) was adopted on May 22, 1990, the day that North Yemen and South Yemen were unified. The flag is essentially the Arab Liberation Flag of 1952, introduced after the Egyptian Revolution of 1952 in which Arab nationalism was a dominant theme. The Arab Liberation Flag served as the inspiration for the flags of both North and South Yemen prior to unification, and the current flags of Egypt, Iraq, Sudan, and Syria.

According to the official description, the red stands for the bloodshed of martyrs and unity; the white for a bright future; black for the dark past.

Before Yemen was united into present-day Republic of Yemen, it was split into North, and South.

The North used the flag on the right (the flag of the Mutawakkilite Kingdom of Yemen), from 1927 to 1962, when it became the Yemen Arab Republic. The flag of the Yemen Arab Republic was the Arab Liberation Flag with a green star in the center of the white band.

Mutawakkilite Kingdom of Yemen (1918-1923)

Mutawakkilite Kingdom of Yemen (1923-1927)

The Republic of Yemen (Arabic: الجمهورية اليمنية‎ al-Jumhūrīyah al-Yamanīyah), commonly known as Yemen ⁱ/ˈjɛmən/ (Arabic: اليَمَن‎ al-Yaman), is a country located in Western Asia, occupying the southwestern to southern end of the Arabian Peninsula. It is bordered by Saudi Arabia to the north, the Red Sea to the west, and Oman to the east. Yemen is considered one of the poorest countries in the Arab world. Its capital and largest city is Sana'a. Yemen's territory includes over 200 islands, the largest of which is Socotra, about 415 km (258 mi) to the south of mainland Yemen, off the coast of Somalia. It is the only state in the Arabian Peninsula to have a purely republican form of government. Approximately 53% of Yemenis are Sunnis, while 45% are Zaydi Shias.

One etymology derives Yemen from yamin, meaning "on the right side", as the south is on the right when facing the sunrise. Another derives Yemen from yumn, meaning "felicity", as the region is fertile. The Romans called it Arabia Felix (Happy Arabia) as opposed to Arabia Deserta (Deserted Arabia), which was their term for northern Arabia.