Sanchez, 22, issued just one walk in the dominant 89-pitch outing Tuesday at Truist Park in Atlanta. Matt Joyce, Jorge Alfaro and Garrett Cooper homered in the 8-0 victory.
"You can sense the excitement with him," Marlins manager Don Mattingly said of Sanchez, the franchise's top prospect.
"We did a good job of being patient and making sure he was built up so he didn't come [to MLB] with [limits]. We were able to build him physically and give him the best chance to just go compete."
Sanchez -- who was called up in late August from the minors -- struck out Braves All-Star Ronald Acuna with a 100.2-mph fastball in his first exchange of the game. The right-handed pitcher issued his lone walk before he retired the next two hitters.
Joyce led off the second frame with his second homer of the season to give the Marlins as 1-0 lead.
Sanchez allowed a leadoff single in the bottom of the inning and then retired 15 of the next 16 batters he faced. Alfaro hit a solo home run in the third inning to double the Marlins' lead.
Cooper hit a two-run bomb in the fourth frame for a 4-0 edge. Alfaro smacked an RBI single to left field in the same inning for a five-run advantage.
Cooper added another RBI single in the seventh inning. Brian Anderson plated Jesus Aguilar with another RBI single in the top of the ninth inning. Marlins outfielder Monte Harrison also scored in the ninth inning when Cooper grounded into a double play for the final run of the game.
Sanchez is now 2-1 with a 1.80 ERA this season. Anderson went 3 for 3 with an RBI and a run scored. Cooper went 2 for 5 with three RBIs. Alfaro went 2 for 4 with two RBIs.
Braves first baseman Freddie Freeman went 2 for 4 in the loss. Braves starter Kyle Wright allowed seven hits and five runs in four innings to drop to 0-4.
"The first three innings, I had issues with my location, but in the fourth inning I started planning on throwing a strike with the first pitch and it worked," Sanchez said of his performance.
The Marlins (19-18) will face the Braves (24-18) at 7:10 p.m. EDT Wednesday in Atlanta.