Rondon, 29, spent his first five seasons with the Chicago Cubs, compiling an 18-13 record with 77 saves, 28 holds and a 3.22 ERA. He went 4-1 with a 4.24 ERA and a career-best 10.83 strikeouts per nine innings last season.
The former closer might be best remembered for his save in Game 4 of the 2015 National League Division Series against the St. Louis Cardinals.
The Astros also announced that they had designated outfielder Preston Tucker for assignment to maintain their full 40-man roster.
Information from The Associated Press was used in this report.