Northwest Semitic is a division of the Semitic languages comprising the indigenous languages of the Levant. It emerged from Proto-Semitic in the Early Bronze Age. It is first attested in proper names identified as Amorite in the Middle Bronze Age. The oldest coherent texts are in Ugaritic, dating to the Late Bronze Age, which by the time of the Bronze Age collapse are joined by Old Aramaic, and by the Iron Age by Sutean and the Canaanite languages (Hebrew, Phoenician/Punic, Edomite and Moabite).

The term was coined by Carl Brockelmann in 1908, who separated Fritz Hommel's 1883 classification of Semitic languages into Northwest (Canaanite and Aramaic), East Semitic (Akkadian, its Assyrian and Babylonian dialects, Eblaite) and Southwest (Arabic, Old South Arabian languages and Abyssinian).

Brockelmann's Canaanite sub-group includes Ugaritic, Phoenician and Hebrew. Some scholars now regard Ugaritic either as belonging to a separate branch of Northwest Semitic (alongside Canaanite) or a dialect of Amorite.

Central Semitic is a proposed intermediate group comprising Northwest Semitic and Arabic. Central Semitic is either a subgroup of West Semitic or a top-level division of Semitic alongside East Semitic and South Semitic. SIL Ethnologue in its system of classification (of living languages only) eliminates Northwest Semitic entirely by joining Canaanite and Arabic in a "South-Central" group which together with Aramaic forms Central Semitic. The Deir Alla Inscription and Samalian have been identified as language varieties falling outside Aramaic proper but with some similarities to it, possibly in an "Aramoid" or "Syrian" subgroup.

It is clear that the Taymanitic script expressed a distinct linguistic variety that is not Arabic and not closely related to Hismaic or Safaitic, while it can tentatively be suggested that it was more closely related to Northwest Semitic.

The time period for the split of Northwest Semitic from Proto-Semitic or from other Semitic groups is uncertain. Richard C. Steiner suggested in 2011 that the earliest attestation of Northwest Semitic is to be found in snake spells from the Egyptian Pyramid Texts, dating to the mid-third millennium BC. Amorite personal names and words in Akkadian and Egyptian texts from the late third millennium to the mid-second millennium BC and the language of the Proto-Sinaitic inscriptions dated to the first half of the second millennium otherwise constitute the earliest traces of Northwest Semitic, the first Northwest Semitic language attested in full being Ugaritic in the 14th century BC.

During the early 1st millennium, the Phoenician language was spread throughout the Mediterranean by Phoenician colonists, most notably to Carthage in today's Tunisia. The Phoenician alphabet is of fundamental importance in human history as the source and ancestor of the Greek alphabet, the later Latin alphabet, the Aramaic (Square Hebrew), Syriac, and Arabic writing systems, Germanic runes, and ultimately Cyrillic.

From the 8th century BC, the use of Imperial Aramaic by the Neo-Assyrian Empire (935–608 BC) and the succeeding Neo-Babylonian Empire (612–539 BC) and Achaemenid Empire (539–332 BC), a form of the Aramaic language, spread throughout the Northwest Semitic region of the Levant, northern regions of the Arabian peninsula and southern regions of Anatolia, and gradually drove most of the other Northwest Semitic languages to extinction. The ancient Judaeans adopted Aramaic for daily use, and parts of the Tanakh are written in it. Hebrew was preserved, however, as a Jewish liturgical language and language of scholarship, and resurrected in the 19th century, with modern adaptations, to become the Modern Hebrew language of the State of Israel.