He came from Tirzah to Samaria to slay Shallum by his own hand, and succeeded him as king (2 King 15:14). He brutally suppressed a revolt at Tiphsah (so the name in the Masoretic text; modern commentators and translators prefer the reading Tappuah, following the Lucian recension of the Septuagint), and ripped unborn children from the wombs of their mothers (15:16). During his reign Tiglath-Pileser III, king of Assyria, invaded Israel with a powerful force, but was induced to leave by a gift from Menahem of 1,000 talents of silver, raised from a levy of 50 shekels on each "person of means" (15:19-21). Tiglath-Pileser records this tribute in one of his inscriptions.

After a reign of about ten years he died, leaving the throne to his son Pekahiah. The author of the Book of Kings describes his rule as one of cruelty and oppression.