Humber gets an $800,000 salary next year. There is a club option for $3 million in 2014 with a $50,000 buyout.
The 29-year-old Humber pitched a perfect game in a 4-0 win over the Seattle Mariners last April 21. It was the highlight of a 5-5 season in which the right-hander made 26 appearances, 16 of them starts.
Humber, who won a national championship in 2003 at Rice, was 9-9 with a 3.75 ERA in 26 starts for the White Sox in 2011. Humber would be familiar with many of the hitters he might face in the upcoming season -- the Astros are switching to the American League next year.
He was a first-round pick in 2004 by the Mets and has also been with the Twins and Royals.