Manager Ned Yost made the announcement Friday before the Royals' exhibition game against Cleveland.
The 38-year-old is a six-time All-Star who last played in the major leagues in 2011 with the San Francisco Giants. He hit .239 with four homers and 26 RBIs in 322 at-bats.
He spent last season with Baltimore's Triple-A team at Norfolk, batting .259 with no home runs and 18 RBIs in 135 at-bats before his release on June 25. The 2002 AL MVP with Oakland, Tejada has a .285 career average with 304 homers and 1,282 RBIs.
Tejada began Friday with a .353 average and three RBIs in 34 spring training at-bats. He will get a $1.1 million, one-year contract when he is put on the 40-man roster. He will have the chance to earn $200,000 in performance bonuses: $40,000 each for 55, 65, 75, 85 and 95 games,
Brett Hayes, the other catching candidate, cleared waivers and was sent outright to Triple-A Omaha.