The Arabian Peninsula (Arabic: شبه الجزيرة العربية, romanized: shibh al-jazīra al-ʿarabiyya, or جزيرة العرب, jazīrat al-ʿarab, 'the Island of Arabs'), or simply Arabia, is a peninsula in West Asia, situated north-east of Africa on the Arabian plate. At 3,237,500 km² (1.25 million sq mi), comparable in size to India, the Arabian Peninsula is the largest peninsula in the world.

Geographically, the Arabian Peninsula comprises Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, the United Arab Emirates (UAE) and Yemen, as well as southern Iraq and Jordan. The largest of these is Saudi Arabia. In the Roman era, the Sinai Peninsula was also considered a part of Arabia.

The Arabian Peninsula formed as a result of the rifting of the Red Sea between 56 and 23 million years ago, and is bordered by the Red Sea to the west and south-west, the Persian Gulf and the Gulf of Oman to the north-east, the Levant and Mesopotamia to the north and the Arabian Sea and the Indian Ocean to the south-east. The peninsula plays a critical geopolitical role in the Arab world and globally due to its vast reserves of oil and natural gas.

The era of human settlement in the Arabian Peninsula predating any systematic written records is known as Prehistoric Arabia. The period of Arabian history beginning with the appearance of systematic records, until the rise of Islam, is known as Pre-Islamic Arabia. In the medieval Islamic period, geographers divided the Peninsula into four main regions: the Central Plateau (Najd and Al-Yamama), South Arabia (Yemen, Hadhramaut and south-western Oman), Al-Bahrain (Eastern Arabia or Al-Hassa), and the Hejaz (Tihamah for the western coast).

In antiquity, the term "Arabia" encompassed a larger area than the current term "Arabian Peninsula" and included the Arabian Desert and large parts of the Syrian–Arabian desert. During the Hellenistic period, the area was known as Arabia (Ancient Greek: Ἀραβία). The Romans named three regions "Arabia":

One of the nomes of Ptolemaic Egypt was named Arabia.

Arabians used a north–south division of Arabia: ash-Sham vs. al-Yaman, or Arabia Deserta vs. Arabia Felix. Arabia Felix had originally been used for the whole peninsula, and at other times only for the southern region. Because its use became limited to the south, the whole peninsula was simply called Arabia. Arabia Deserta was the entire desert region extending north from Arabia Felix to Palmyra and the Euphrates, including all the area between Pelusium on the Nile and Babylon. This area was also called Arabia and not sharply distinguished from the peninsula.

The Arabs and the Ottoman Empire considered the west of the Arabian Peninsula region where the Arabs lived 'the land of the Arabs'—billad al-'Arab (Arabia), and its major divisions were the bilad al-Sham (Levant), bilad al-Yaman (Yemen), and bilad al-'Iraq (Iraq). The Ottomans used the term Arabistan in a broad sense for the region starting from Cilicia, where the Euphrates river makes its descent into Syria, through Palestine, and on through the remainder of the Sinai and Arabian peninsulas.