Chen signed for $2 million plus performance bonuses just one day after the club pulled in another free agent left-hander, Jeff Francis. Both contracts are pending physical examinations.
"I'm very pumped, and I'm very happy, and this is the team I want to help," Chen said. "Today has been a very good day."
This broadens the Royals' rotation possibilities to those two veteran lefties plus right-handers Luke Hochevar, Kyle Davies, Vin Mazzaro, Sean O'Sullivan and a pack of young prospects.
"He was in our rotation last year, and certainly we've got a lot of depth and competition at this point, but he should be certainly one of the favorites to win a spot," general manager Dayton Moore said.
Chen had been seeking a multiyear contract as a free agent.
"I always wanted to be back here, and when it became apparent I wasn't going to get a two-year deal, then I tried to work things out with Kansas City for a one-year deal," Chen said.
"And with the signing of Francis, I was even more excited, because I felt like we were going in the right direction, and we feel like we can win this year."
There was an odd twist to the 2010 season. Zack Greinke was coming off a Cy Young Award year, and Chen began the season with Triple-A Omaha. Yet when the final stats were posted, Chen had a 12-7 record to Greinke's 10-14, and both finished with the same ERA, 4.17.
Now Chen is coming back, and Greinke has been traded to the Brewers.
"It was crazy," Chen said. "Zack Greinke is a very, very good pitcher, and we're going to miss him a lot, but we got some really good players in return."
Moore doubts there will be any more free-agent signings or deals before Spring Training.
"I think we're pretty set," he said. "I think we'll go into camp with what we've got at this point unless something opens up that we're not aware of."
Chen, 33, was plucked from near obscurity by the Royals before the 2009 season. He'd undergone Tommy John surgery, and after 10 Major League seasons, his career was on shaky ground. But he kept getting stronger and peaked toward the end of last season.
"Bruce had an exceptional year for us last year," Moore said. "Between him and [Joakim] Soria, they were the two most consistent pitchers on our staff. He has a lot of pitching skills and just kept getting better and better."
Chen's 12 wins were the most by a Royals left-hander since Charlie Leibrandt won 13 and Floyd Bannister won 12 in 1988. Chen worked six perfect innings in a July 3 victory over the Angels and posted a two-hit shutout over the Rays on Oct. 1.
"As the season progressed, I thought I finished stronger, my pitches were better and I had better command," he said. "I basically applied everything I had learned about myself."
Chen lives in Surprise, Ariz., site of the Royals' training complex, and has been working out there. He's well aware of the large contingent of young pitchers, many of them lefties, who will be in camp.
"It's very good for the organization," he said. "I've seen a couple of the guys -- [Danny] Duffy, [Mike] Montgomery and [John] Lamb -- and I think they're a very talented group. The Royals are going to be good for a long time."
In that scenario, Moore sees a plus in the signings of Chen and Francis.
"It puts us in a position where we don't to have to rush any of our young kids," Moore said. "It just keeps them going a step at a time."
Chen also has the reputation of being a good guy to have in the clubhouse.
"Terrific," Moore said. "He's got great leadership skills, and I know that his teammates will be very excited that he's back."
Yep, after years of few left-handed pitchers on the Royals' roster, they just keep coming.
"And we're going to keep signing them -- out of the Draft and everywhere else," Moore said.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.