The deal is contingent on Myers passing a physical.
Myers' deal includes a mutual option for 2011. He also can earn additional performance bonuses, according to The Associated Press.
The 29-year-old right-hander has played all eight of his major league seasons with the Phillies, going 73-63 with a 4.40 ERA. He was 4-3 with a 4.84 ERA in 10 starts and eight relief appearances last year, when he made $12 million.
Myers tore the labrum in his right hip in May and underwent surgery in June. He missed a rehab start in August after an eye injury, finally returned in September and made eight relief appearances in the last month of the regular season.
Myers made his major league debut with the Phillies in July 2002, when current Astros general manager Ed Wade was the Phillies' GM. Myers' best season was in 2005, when he went 13-8 with a 3.72 ERA in 34 starts, including two complete games. He was given a $25.75 million, three-year contract in February 2007, moved to the bullpen that season and saved 21 games.
Philadelphia acquired Brad Lidge from the Astros that offseason and Myers returned to the rotation. He went 10-13 with a 4.55 ERA in 30 starts in the regular season, then was 2-1 in the postseason to help the Phillies win the World Series.
Myers will rejoin former Philadelphia teammate Pedro Feliz, who agreed to a one-year contract with Houston at the winter meetings.
His agreement was first reported by KRIV-TV in Houston.
Also Friday, the Astros and 27-year-old right-hander Josh Banks agreed to a minor league contract. Banks went 7-7 with a 3.46 ERA in 17 starts and nine relief appearances last season for Triple-A Portland. Banks made six appearances for San Diego last season and has made 18 career major-league starts.
Houston also agreed to one-year contracts with catcher J.R. Towles ($406,500) and infielder Chris Johnson ($400,000) and released Ryan Sadowski from his minor league contract, allowing the right-hander to sign with a South Korean club.
Information from The Associated Press was used in this report.