"He's been around the Cactus League. He's a guy our scouts liked," said Padres manager Bud Black. "It's always nice to have some experienced catching in your Minor League system."
The Padres sent cash considerations or a player to be named to the Royals in the deal.
Moore comes to the Padres organization with a strong reputation as being a good catch-and-throw guy.
The team officially lost left-handed reliever Patrick Schuster, who was claimed on waivers by the Royals. Schuster was told Monday that he wasn't going to make the team's 25-man Opening Day roster.
Moore, who is a career .200 hitter in 271 plate appearances over five seasons in the Major Leagues, will head to Triple-A El Paso.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.