Emathia (Greek: Ἠμαθία, romanized: ēmathía) is an ancient toponym for an area of Macedonia on the Thermaic Gulf between the Pierian range and the Axius (Vardar). Some ancient geographers give it as the name of a town in the region, or as a name in alternation with Macedon. In later poetic use, the name may vaguely refer to regions as disparate as Thessaly and Thrace. Etymologically, the homeric name suggests the meaning "sandy." It was used by several classical authors as a synonym for Bottiaea or even all of Macedon. The Imathia regional unit of Greece is named after the historic region's name.

The sole homeric reference to Emathia comes from the Iliad (c. 800 BCE) as a place on Hera's journey from Olympus to Ida:

Hera in a flash of speed left the horn of Olympos / and crossed over Pieria and Emathia the lovely / and overswept the snowy hills of the Thracian riders / and their uttermost pinnacles, nor touched the ground with her feet. Then / from Athos she crossed over the heaving main sea / and came to Lemnos, and to the city of godlike Thoas.

— Homer, Iliad 14.225-30, tr. Lattimore

As Richard Janko reconstructs it, "the first leg of Her[a]'s journey takes her down the N.E. foothills of Olumpos (Pieriē) and along the Macedonian coast (Emathiei) to the 'snowy mountains of the Thracians', which are neither the Rhodope range nor Mt Pangaion behind Amphipolis (both too far N.E.). but Mt Athos itself to the S.E., whence she crosses the sea, in the same direction to Lemnos." Hera's path, which combines the notions of flight and stepping from pinnacle to pinnacle, suggests the shore-hugging navigation familiar to Greek sailors, and an island hopping traversal of the northern Aegean. An hellenistic scholion to Il. 14.226 explains that Emathia was a former name for Macedon, and lay by Thrace.

The name is reminiscent of the a homeric formula for Pylos (Greek: Πύλον ἠμαθόεντα, romanized: púlon ēmathóenta, lit. 'sandy Pylos') which appears 13 times in the homeric corpus, and once in the hesiodic Shield of Herakles.

A scholion to Theogony 985 attempts to connect Emathion, the son of Eos (dawn) mentioned there, with Emathiē, though West argues against this association, preferring to place him in Ethiopia in Arabia. The name may derive from either ēmati (Greek: ἤματι, romanized: ēmati, lit. 'daily') or amathos, "sand."

By the time Emathia appears in history, it is already gone. In its place stands kato Makedonia, "Lower Macedonia," as it was when it was about to be attacked by Sitalces, Thracian king of the late 5th century BC. Perdiccas II of Macedon of the Temenid Dynasty was the Macedonian king. Alexander I of Macedon, his father, "and his forefathers" had conquered Emathia earlier and had renamed it to Macedonia. These are the events described by Thucydides (Book II.99), considered their most credible narrator, because his account corresponds to that of Herodotus, their first author. Thucydides describes also Upper Macedonia (epanothen) as Macedonian also, but the original Macedon, he says, was the lower.