The move was effective immediately, with Kuntz taking over Sisson's duties as first base, baserunning and outfield coach.
Sisson, 48, was in his second season on the Royals' coaching staff. He was in the organization as the Royals' Minor League field coordinator during the previous three years.
Kuntz, 57, was serving as special assistant to general manager Dayton Moore as an outfield, bunting and baserunning coach in the Minors this year. He was previously the Royals' Major League first base coach for parts of three seasons.
"Doug was a guy who worked his tail off, but as an organization, we thought it was time to make a change," manager Ned Yost said. "Rusty was available, and working as a Minor League outfield and baserunning coordinator with all our young kids, and we're lucky to have Rusty -- he's one of the best in the business."
No specifics were cited by Yost for Sisson's dismissal, but he said it was purely a baseball decision and not affected by outside issues.
Sisson was often credited with giving the Royals' outfielders the work they needed to lead the Majors in assists last year, and they are on top again this year with 28. He also worked to increase the Royals' baserunning aggressiveness, and they finished second in stolen bases in the American League last year, although their output has dropped this season.
Yost said the change will not signal any de-emphasis on the baserunning attack under Kuntz.
"That was part of his job description and job title in the Minor League system, and he's an excellent baserunning coach," Yost said.
Kuntz, a big league outfielder with the White Sox, Twins and Tigers, is remembered as driving in the World Series-deciding run for Detroit in 1984. He has been a coach with the Pirates, Braves, Marlins, Mariners and Astros.
He's known for his good nature and ebullient personality, as well as his knowledge of the game.
"Rusty's been in this organization for a long time. We felt a change was warranted, and we brought Rusty back," Yost said. "Doug did a great job for us, [but] we felt a change was needed. Rusty is the one who made Alex Gordon a left fielder, he's been with (Jarrod) Dyson and (Lorenzo) Cain, working with them."
Kuntz lives in Overland Park, Kan., with his wife Salli. Their son, Kevin, plays baseball at the University of Kansas.
Kuntz reported to Kauffman Stadium in time for batting practice on Saturday.
"I got a call this morning saying, 'Can you come here, help out?' So I was assuming I was going to throw some BP, and ... when I walked into the locker room, I had a helmet in my hand. I assume I'm going to be a base coach again," Kuntz said.
"Other than that, I have no clue yet, because I haven't met with anybody to know what happened, but it's probably none of my business anyway. I'm happy to be back. I love all these guys, I've known them all, had some of them here and had most of them in the Minor Leagues."
This is the second time that Kuntz has been called in for an in-season coaching change. After Yost took over as manager from Trey Hillman in May 2010, Kuntz was brought in to replace third base coach Dave Owen. He coached first base for the rest of the season, with Eddie Rodriguez switching to third. Sisson took Kuntz's place for the 2011 season.
Other coaching changes in Yost's tenure took place before the current season, when Chino Cadahia replaced John Gibbons as bench coach and Dave Eiland took over for Bob McClure as pitching coach.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.