Lyon gave up a lead-off single in the ninth inning, but then retired the next three batters to collect his 20th save of the season. The Astros became the fifth team in major league history to have two pitchers with 20 or more saves in the same season.
Matt Lindstrom has 23 saves.
Figueroa (6-4) gave up six hits and struck out five over 6 2/3 innings. He ended a two-game skid and the Astros won for just the second time in eight games.
Carlos Lee doubled home a run in the first inning and the other Houston score came when Lee dashed home from third on a fielder's choice grounder off the bat of Brett Wallace.
Johnny Cueto (12-7) suffered his third straight loss, allowing two runs on eight hits in seven innings.
Cincinnati will host Houston again Thursday and then entertain Milwaukee for three games before taking part in the playoffs for the first time in 15 years.
Teacher apologizes for showing sexual image of herself in class
Susan Sarandon 'very excited' about daughter's pregnancy