Willis, who spent Thursday in Detroit handing out Christmas gifts to children at a charity event, said he's already starting to feel embraced by the city. He grew up in the San Francisco Bay area in a single-parent household and his mother worked as a welder, so he has a blue-collar background.
"Hard work pays off," Willis told ESPN.com. "This is truly a blessing for me and my family. I'm really appreciative that the Tigers believed in me enough to even offer me a deal. That speaks volumes."
Agent Matt Sosnick said Tigers president and CEO David Dombrowski and vice president John Westhoff helped bring the deal to completion quickly. The negotiations spanned about four days.
"We felt like the commitment on their part was fair, and Dontrelle really wanted the stability of knowing he'll be here for a while," Sosnick said. "The deal still allows him to be a free agent again when he's 28 years old. If everything goes well and his body holds up, he probably has his two big contracts ahead of him."
The deal includes incentives that could raise the total value of the package to more than $30 million.
Willis, 25, has a 68-54 record an a 3.78 ERA in parts of five seasons with the Marlins. He went 10-15 with a 5.17 ERA last season.
"I pitched through some injuries, but they checked me out and
everything will be OK," said Willis, who was hampered by forearm
tightness last season. "I was healthy the last couple of weeks and
I think that's what the Tigers saw that made them interested."
Willis earned a base salary of $6.45 million for the Marlins last year. He would have been eligible for free agency after the 2009 season, but is now locked up through 2010.
"We're absolutely thrilled to accomplish this and keep him a part of our organization for a lengthy period," Dombrowski said.
Jerry Crasnick is a senior baseball writer for ESPN.com. The Associated Press contributed to this report.