Verlander returns to Houston, where he starred after arriving via trade from the Detroit Tigers in August 2017 until he entered free agency last fall.
Verlander, 40, has a 6-5 record and 3.15 ERA this season, including a 1.69 mark over his past six starts, in which he held batters to a .167 average and just one home run in 37 innings. The three-time Cy Young Award winner earned his 250th career victory Sunday.
Verlander is under contract through next season with a potential option for 2025 after agreeing to an $86.7 million, two-year contract with the Mets in December.
The Mets, 50-55 and in fourth place in the National League East, have been one of baseball's biggest disappointments this season under third-year owner Steve Cohen. They currently sit 17 1/2 games back of the Atlanta Braves in the division and six games out of a wild-card spot.
Verlander would have a chance to contend with the Astros, who are half a game behind the Rangers in the American League West and currently slotted into a wild-card spot.
ESPN's David Schoenfield and The Associated Press contributed to this report.