The Orioles were able to set the early tone by keeping the left-hander on his heels.
Joey Rickard, Mark Trumbo and Trey Mancini clobbered first-inning homers off Gonzalez, and Baltimore held off the Nationals 6-4 on Monday night.
The Orioles (21-10) increased their winning streak to a season-high five games. The Nationals (21-11) fell to 14-26 all time in Baltimore.
"He's been very quietly one of the more consistent starters in baseball really," Showalter said about Gonzalez. "You've got to throw him in there with a lot of guys. He makes 30 starts every year and gives his team a chance to win, so you better not let him get his feet on the ground or it can be a long night."
Kevin Gausman (2-3) was back on the mound for Baltimore after being ejected in the second inning of his last start, Wednesday against the Boston Red Sox. Gausman was sharp, holding the Nationals to two runs on five hits with eight strikeouts and one walk over seven innings -- his longest outing of the year.
"It was big for me," Gausman said. "Wish I had been able to do that last start, but obviously some things happened. It was just good to go out there and feel like myself."
Catcher Matt Wieters, who spent eight years with the Orioles, returned to Camden Yards for the first time since signing with the Nationals in February. He received a standing ovation in his first at-bat and went 1-for-4, including an RBI double off Brad Brach in the ninth that cut the margin to 6-4.
Brach then got his eighth save when Brian Goodwin grounded out and Adam Lind was caught in a rundown between third and home for a double play to end the game.
Orioles catcher Caleb Joseph tied a career high with four hits.
Bryce Harper was also back in the lineup for Washington after missing the previous three games with a groin injury. Harper had an RBI single in the sixth and then homered two innings later to pull the Nationals within 6-3.
Gonzalez (3-1) allowed six runs on seven hits with two strikeouts and four walks over six innings.
"The only thing that beat us tonight was the long ball," Gonzalez said. "Other than that, I think we did a hell of a job. We pounded the strike zone, went after them. I felt like I was more in the zone than I was previously."
Rickard gave the Orioles a 1-0 lead when he hammered Gonzalez's fourth pitch of the game over the left field fence. Trumbo followed with another solo shot, and two batters later, Mancini hit a two-run homer. Entering the game, Gonzalez had allowed just four home runs over his past 38 1/3 innings.
"Early, he was not hitting his spots," Nationals manager Dusty Baker said. "He was supposed to throw one ball away and it was in. Another pitch was supposed to be in and it got away. He settled down after the number of home runs they hit in that inning. He was throwing the ball well."
Gausman retired 10 straight batters before Jayson Werth flared a single in the fourth.
The Orioles increased the lead to 6-0 in the bottom half of that inning on an RBI single by Joseph and a throwing error by Nationals third baseman Anthony Rendon.
Washington got on the board when Michael Taylor hit a two-out, RBI double in the fifth.
NOTES: Nationals INF Stephen Drew (hamstring) could begin a rehab assignment this weekend, manager Dusty Baker said. Drew has not played since April 11. ... Orioles 2B Jonathan Schoop was back in the lineup after missing the previous two games with an injured right wrist. He had a double in the fourth and has reached base for a career-high 23rd straight game. ... Washington recalled OF Brian Goodwin from Triple-A Syracuse on Monday. To make room, OF Rafael Bautista was sent down to the Chiefs.