Prewett is a surname. Notable people with the surname include:
Prewett family, fictional characters in J. K. Rowling's Harry Potter series Gideon and Fabian Prewett, Molly Weasley's brothers
Frank Prewett (1893–1962), Canadian poet, who spent most of his life in the United Kingdom Park Prewett Hospital, psychiatric hospital northwest of Basingstoke, England, which operated from 1917 until 1997
See also Prue Watt Pruett