The former Cy Young Award winner will start Game 1 for the third consecutive series for the Rays, who beat the New York Yankees 2-1 in Game 5 on Friday to advance.
Snell last pitched Monday in a 9-3 loss to the Yankees in Game 1, giving up four runs on six hits in five innings. He had four strikeouts and two walks.
Overall, Snell was 4-2 during the 2020 regular season, with a 3.24 ERA and 63 strikeouts.
The Astros have yet to name their starter for Game 1.