"It's good to be back," said Qualls, who secured the first multiyear deal of his career.
The 35-year-old right-hander spent last season with the Marlins and went 5-2 with a 2.61 ERA in 66 relief appearances. He induced 11 double-play balls, which tied for third among National League relievers, and he ranked fifth in the NL in ground-ball percentage (77.7 percent).
Qualls has made 50 or more appearances in nine consecutive seasons (2005-13) and since his debut in 2004, ranks second among all Major League relievers with 663 appearances. His signing bolsters a young bullpen that struggled to close out games last season.
Qualls returns to Houston, the organization that drafted him in the second round of the 2000 First-Year Player Draft. He made his debut in 2004 and made three appearances in the 2005 World Series, giving up a crucial grand slam to Paul Konerko in a Game 2 loss. He made 262 appearances with the Astros and was 23-12 with six saves and a 3.39 ERA.
Qualls thinks the Astros are headed in the right direction and wants to be a part of the upswing.
"I think once new ownership took over, they had to see what they had," Qualls said. "They wanted to see what kind of talent they have with their kids and who they wanted to build around. Once they realized their plan, they could go out and get a few guys and trend towards winning again.
"When I was there, the city was amazing with the way they supported the team. I would like to get that buzz around the city again. It's definitely going in the direction."
Astros general manager Jeff Luhnow said Qualls' role in the bullpen is yet to be determined. Houston relievers posted a league-high 4.90 ERA last season and blew 29 saves, which tied for the most in baseball in 2013.
"All the roles in our bullpen are up for grabs," Luhnow said. "It's really going to be up to [manager] Bo [Porter] and our staff to determine who gets what role. Everything is open right now. Chad's going to have an important role in our bullpen. He had a good year last [season] and his velocity ticked up. He's got a real good slider to go with a good fastball. He gets a lot of ground balls."
Qualls is ready to take any spot in the bullpen, but he'll be counted on to be a leader.
"Even going back to my Houston days, I can throw the seventh, eighth, ninth," he said. "When I was in Miami last year, it was the same situation. It was a team that didn't win many games and was rebuilding. I came in and all the guys in the bullpen gravitated towards me and I did my thing. Hopefully this year's bullpen here in Houston, I get to meet some of the guys and get to know them and help them whenever I can."
The reliever is the third acquisition by the Astros this week. They traded for Rockies center fielder Dexter Fowler on Tuesday and signed free-agent starter Scott Feldman to a three-year contract on Friday. Feldman will make $30 million over three years, meaning the Astros have added $20.35 million in payroll for next season between Fowler, Feldman and Qualls.
Luhnow would still like to add another reliever, as well as possibly a starting pitcher and another bat.
"We still feel like we need to at least get another pitcher of [Qualls'] caliber," Luhnow said. "We feel pretty good. We've had some conversations, but I can't tell you if anything is going to happen soon."
The Astros traded Qualls to Arizona following the 2007 season, along with Chris Burke and Juan Gutierrez, for Jose Valverde. He now lives in Austin with his wife, Tara, and their two sons, aged 4 1/2 years and five months.
"I was there at the beginning of my career, and now I have family here in Austin and my wife is from Houston, so it feels pretty good family-wise as well," he said. "It's good to go somewhere you're wanted and you know well."
Qualls has pitched for eight different organizations in his career, including time with Houston (2004-07), Arizona (2008-10), Tampa Bay (2010), San Diego (2011), Philadelphia (2012), New York Yankees (2012), Pittsburgh (2012) and Miami (2013). In his 663 career appearances, Qualls has gone 45-37 with 51 saves and a 3.79 ERA.