Butler, the Royals' player of the year, agreed to a deal worth $470,000 — a raise from $421,000.
The first baseman led the team in 2009 with a .301 average, 93 RBIs and 51 doubles. His doubles were second-most in the majors and his 73 extra-base hits were tied for sixth.
Callaspo hit .300 with 41 doubles, eight triples, 11 home runs and 73 RBIs. He will receive $460,000.