The Twins will receive either a player to be named or cash for the 39-year-old veteran.
Earlier in the day, the Royals put Miguel Tejada on the 15-day disabled list with a strained right calf. The 39-year-old Tejada, who hurt himself diving for a ball on Saturday, was hitting .288 in 53 games and had won the starting second base job.
Carroll singled and scored for the Twins in their 5-2 win over the Chicago White Sox. He is hitting .230 with nine RBIs.
"If I can go there and contribute in a positive way, I know the team is playing extremely well right now and they have a bunch of good young guys and some great pitching," Carroll said. "It should be exciting to get over there and get in that clubhouse."
Royals manager Ned Yost was eager to have him.
"Jamey Carroll is a pro's pro," Yost said after the Royals beat Boston 4-3. "He's a very solid player. He hits left-handed pitching very well. He can play second, third and short in that order. Those are about his best positions. He'll give you a real quality at-bat."
"Miguel's injury kind of put a hole over there right now for us," he said. "We'll play him at second. When Moose (third baseman Mike Moustakas) needs a break, we can play him at third. He's a very proficient third baseman, too."
The Twins will make a corresponding roster move on Monday.
"As much as anything, this is a deal for Jamey Carroll to go on a team that's in a playoff race and go over there and add his professionalism and experience to that club and give them an opportunity to get into a race," Twins assistant GM Rob Antony said.