The tall, right-hander was claimed off outright waivers by Kansas City on Friday from the Chicago Cubs. Volstad becomes the 40th player on the Royals' 40-man roster.
Volstad, 26, was 3-12 with a 6.31 ERA in 21 starts for the Cubs last season. He was acquired by the Cubs from the Miami Marlins last January in a trade for pitcher Carlos Zambrano.
Opening the season in the Cubs' rotation, Volstad went 0-7 in nine starts and was optioned to Iowa on May 18. He was 3-5 with a 5.17 ERA in 12 starts for the Triple-A club. Oddly, Volstad had virtually the same stats after rejoining the Cubs on Aug. 1 -- 3-5 and a 5.18 ERA in 12 starts.
His victory over Colorado on Aug. 26 broke a 24-start winless streak for him. His last previous win had been for the Marlins on July 10, 2011, against Houston. In four seasons with the Marlins, he made 102 starts and one relief appearance, compiling a 32-39 record and a 4.59 ERA.
The Cubs' front office had hinted that Volstad did not figure in their 2013 rotation plans, but Royals general manager Dayton Moore said that Volstad will be in the mix as KC sorts through its starting candidates. Beefing up the starting pitching is a priority for the club this offseason.
"We want to be aggressive with our pitching," Moore said. "He's a big, strong guy who is still young, and we hope to get him back on track."
Volstad's best season was 2010, when he made 30 starts and had a 12-9 record with two complete games and a 4.58 ERA. He made 29 starts in each of two other seasons.
A sinkerballer, Volstad won his first Major League start for the Marlins on July 11, 2008, when he held the Dodgers to one run in 8 2/3 innings.
His history includes a six-game suspension and a $4,000 fine in 2010 after he threw at the Nationals' Nyjer Morgan, who charged the mound and ignited a bench-clearing ruckus. Morgan drew a harsher penalty -- eight games and $15,000.
A first-round choice in the 2005 Draft by the Marlins and 16th overall, Volstad played at Palm Beach Gardens High School in Florida.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.