Josaiah is a modern form related to Josiah, the Hebrew biblical name meaning "Yahweh supports" or "heals."
Josaiah is a variant spelling of the ancient Hebrew name Josiah — one of the most historically significant names in the biblical canon. The original Hebrew Yoshiyahu (יֹאשִׁיָּהוּ) carries the meaning "God supports" or "God heals," a theophoric name in the tradition of Hebrew names that invoke divine sustenance and care. The name belongs to Josiah, the reformer-king of Judah who reigned in the seventh century BCE and whose story is told with rare sympathy in the Second Book of Kings.
Josiah came to the throne as a child, cleansed the Temple in Jerusalem, rediscovered the Book of the Law, and instituted sweeping religious reforms — making him one of the few kings in the Hebrew Bible described as doing "what was right in the eyes of the Lord." The name Josiah traveled through the Septuagint into Christian tradition and was carried by Puritan families in colonial New England, who favored Old Testament names for their scriptural weight. Josiah Wedgwood, the eighteenth-century English potter and abolitionist, and Josiah Quincy, the prominent Massachusetts political figure, helped establish the name in Anglo-American civic life.
The great American statesman and inventor Josiah Bartlett signed the Declaration of Independence. The spelling variant Josaiah adds a visual distinctiveness to the ancient name — an extra syllable's worth of breath and emphasis — while preserving its full biblical resonance. In contemporary African American and Caribbean communities, where Old Testament names have long been embraced for their strength and spiritual depth, Josaiah has found particular warmth. The spelling variant also signals intentionality: parents who choose it are making an active choice to distinguish their child while honoring a lineage of royal and prophetic bearing.