The Royals acquired Misiewicz from the Mariners on Monday in exchange for cash considerations. He was optioned to Triple-A Omaha.
Though he won't be joining the big club as he changes organization, Misiewicz will recapture a 40-man roster spot after Seattle designated him for assignment over the weekend. The 27-year-old southpaw owns a 4.48 ERA and 1.38 WHIP across 88.1 innings over parts of three seasons in the majors.