Hayes, 28, was claimed on waivers Nov. 2 from the Marlins. He was the Marlins' backup catcher for parts of four seasons, and this year, he batted .202 in 39 games. A right-handed batter, he has a .217 average in 143 games.
A strong defensive catcher, Hayes has thrown out 19 of 74, or 26 percent, of would-be basestealers in his Major League career.
Hayes is one of two catchers on the Royals' 40-man roster, along with regular Salvador Perez. Brayan Pena and Adam Moore were designated for assignment on Tuesday and Manny Pina is on the Triple-A Omaha roster.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.