Myers (4-13) gave up one run on four hits while striking out six without issuing a walk. It was his first win since June 17, when he threw a complete game in a 7-3 victory over the Los Angeles Dodgers.
In between, Myers has given the Astros plenty of opportunities to win games, said manager Brad Mills. They were finally able to cash in on one.
"He threw the ball outstanding," Mills said.
Mark Melancon worked a scoreless ninth to earn his 17th save of the season.
Humberto Quintero finished 2-for-4 with a double and three RBI, while Jimmy Paredes added three hits and an RBI for the Astros, who snapped a four-game skid.
Jones said Myers' curveball and slider were working.
"He was able to keep the ball down," said Jones. "But I thought we did square up some balls. ... We hit some balls hard, but just right at some guys."
Brad Lincoln (1-2) pitched well in defeat, giving up two runs on five hits over six innings while fanning six without walking a batter.
Houston struck first and remained in front for good, plating a pair of runs in the second inning. Carlos Lee led off with a single to right, stole second and advanced to third on a single by Brian Bogusevic to give the Astros runners on the corners with no outs. Lee crossed the plate on a groundout by Paredes, and Paredes touched home two batters later on a double by Quintero.
Doumit hit a two-out solo shot to right-center in the bottom of the second for eighth homer of the season.
Pittsburgh got a leadoff double from Jones to begin the home fourth, but were unable to tie the game as Myers induced a groundout from Andrew McCutchen, caught Derrek Lee looking and got Neil Walker to nub one back to the mound to end the inning.
The Astros had an excellent chance to widen their lead in the seventh, but couldn't. Paredes led off with a base hit against Chris Resop and Clint Barmes singled to left, but was retired at second when Quintero grounded into a force out. With runners at the corners, Myers attempted to put down a squeeze bunt, but knocked it right back to Resop, who flipped to Doumit at home in time to get Paredes charging down the third base line. Jordan Schafer then struck out to end the threat and keep it a one-run game.
Pittsburgh wasted another scoring opportunity in the eighth when pinch-hitter Josh Harrison cued a ball back to Myers and wound up on second thanks to a wide throw. Reliever Wesley Wright came in and walked Alex Presley to put two runners on with two down. Wright then went to a 2-0 count on Jones before getting him to loft a fly ball to right to end the inning.
The Astros added two insurance runs in the ninth. Bogusevic drew a leadoff walk and Paredes ripped a double into the left-center field gap that went just off the glove of McCutchen to put runners on second and third. Following a Barmes strikeout, Quintero slapped a two-run single into left to account for the final margin.
Houston is 22-49 on the road this season...The Astros lead the National League with 279 doubles this season...Pirates manager Clint Hurdle is one win short of 600 in his managerial career...Pittsburgh still leads the season series with the Astros, 10-7...Prior to the game, the Pirates recalled third baseman Pedro Alvarez, who went 0-for-3, and pitchers Jeff Locke, Aaron Thompson and Daniel Moskos from Triple-A Indianapolis. They also selected pitcher Jared Hughes from Indianapolis and recalled pitcher Evan Meek from his rehab assignment, reinstating him from the 60-day disabled list. Moskos entered the game in the top of the ninth and got the final two outs of the inning with one strikeout. The Pirates also transferred pitchers Kevin Correia and Paul Maholm to the 60-day disabled list.