The right-handed reliever agreed to a two-year contract Saturday with a team option for 2016. The deal is for $6 million guaranteed with a $3.5 million option in 2016, sources told ESPN.com Insider Keith Law.
Qualls went 5-2 with a 2.61 ERA in 66 games for the Miami Marlins this year and has made at least 50 appearances in nine straight seasons. He has pitched for eight clubs in his big league career, going 45-37 with 51 saves and a 3.79 ERA in 663 appearances.
"Improving our bullpen is a top priority this offseason," Astros general manager Jeff Luhnow said in a statement. "Bringing Chad back to Houston is a big step in that direction."
The move came one day after Houston added a veteran starter in 30-year-old Scott Feldman, who signed a three-year deal. The young Astros had the worst record in the majors last season at 51-111, losing their last 15 games.
The 35-year-old Qualls was drafted in the second round by Houston in 2000 and pitched for the Astros from 2004-07, helping them reach their only World Series in 2005.
Information from The Associated Press was used in this report.