Wakamatsu will serve as the Royals' bench coach and catching instructor after working as a special assignment scout for the New York Yankees this past season. Jirschele, who has managed Kansas City's Triple-A affiliate in Omaha since 2003, will be a coach.
Former Cubs manager Dale Sveum, who joined the Royals earlier this month, will serve as third base coach and oversee infield instruction.
Wakamatsu served as the manager of the Mariners in 2009 and much of 2010. Jirschele has been in the Royals' organization since 1992 and has been the manager of the Omaha Storm Chasers for the last 11 seasons.