"The choice to come here is driven from the top down," Fister said Thursday after agreeing to a $7 million, one-year contract. "We're trying to win a World Series here, and that's your ultimate goal. That's why you come to the ballpark every day."
Fister can earn an additional $5 million in performance bonuses based on innings: $1 million each for 100, 125, 150, 175 and 200.
He was 5-7 with a 4.19 ERA in 15 starts and 10 relief appearances last season for Washington. He was 16-6 with a 2.41 ERA for the Nationals in 2014, when he finished eighth in NL Cy Young Award voting.
"We feel good about the person that we're getting as well as the pitcher that we're getting," Astros general manager Jeff Lunhow said. "There were other options out there. We looked at a lot of them, but we feel good about this as the piece that makes the Astros the strongest for 2016."
The 31-year-old right-hander is 65-63 with a 3.42 ERA 167 starts and 13 relief appearances in seven major league seasons that also included time with Seattle (2009-11) and Detroit (2011-13). His 1.77 walks per nine innings is the lowest among active pitchers with 1,000 or more innings.
"I know Doug Fister makes us better," manager A.J. Hinch said. "I know he's going to make big starts for us and, ultimately, when you wake up in January and you're in the manager's chair and Jeff calls and says we've got Doug Fister signed to a contract, I wake up a pretty happy man."
Coming off its first postseason appearance in a decade, Houston projects to have a starting rotation that includes AL Cy Young Award winner Dallas Keuchel, Collin McHugh, Mike Fiers and Lance McCullers. Scott Feldman and Brad Peacock also are options.
"Having guys like that to kind of lead the staff that's important," Fister said of Keuchel. "Kind of sets the tone for everybody. As a pitching staff we work together. I've been blessed to be on some great teams, and I certainly feel blessed to be on this one."