Colon, 26, was optioned to Triple-A Omaha while the club selected the contract of infielder Dusty Coleman, who played collegiately at Wichita State and spent the last seven years in the Oakland organization before signing this offseason with the Royals.
Coleman made his Major League debut in Friday night's 3-2 walk-off win over the Twins.
In the ninth with the game tied at 2 and runners on first and second, Coleman came in to pinch-run for Salvador Perez at second base. Omar Infante's sacrifice bunt moved the runners to second and third with one out.
Colon, the fourth overall pick of the 2010 MLB Draft, has played in just seven games since May 31. He was hitting .244 with a .601 OPS.
"Young guys tend to get stagnant when they don't play a lot," manager Ned Yost said. "We didn't want that to happen to him so we'll send him out and get him playing every day.
"As long as everyone is healthy, it doesn't make any sense having him sit here. We'll get him going [at Omaha], playing third and short and second, so in case something does happen here with an injury, he's ready."
Coincidentally, Coleman, 28, and his wife moved to Shawnee, Kan., a suburb of Kansas City, a few years ago.
"I was ecstatic," Coleman said. "Brian Poldberg, the [Omaha] manager, told me that I messed up and I wasn't gonna get to go to the Pan Am Games, and I was like, 'What? What's going on?' Then he said that I was going to Kansas City. So I'll take it. It's an honor to be here."
Coleman was hitting .304 with 17 doubles, seven homers and 35 RBIs combined in stops at Double-A Northwest Arkansas and Omaha.
After seven long years in the Oakland organization, Coleman admits he was starting to lose faith in his dream of playing the big leagues.
"It's definitely been a journey with a lot of ups and downs, a few injuries here and there," he said. "I'm just trying to stay focused on the ultimate goal, getting up here and grinding every day. Luckily, I just needed a few breaks and they came with Kansas City.
"There was definitely times where I was like, 'Am I called to do this still?' Just kind of felt like I was still saying, 'Hey, baseball's going to give you a shot,' and here I am."